Basically the app was designed to be used by party caucus leaders (rather than all the caucus voters) to (1) report results upstream to party leadership
and (2) implement the "caucus math" which is necessary in Iowa because of the rather complicated two-round voting system used.
the app again [i.e. as in 2016] would be downloaded onto the personal smartphones of the caucus precinct and party leaders, and not onto party-provided hardware.
The Iowa Democrats' app will theoretically allow the state party to report the results much quicker than a phone-based system, and it may also help local party leaders with what's referred to as "caucus math."
A party manual says the app will "automatically calculate the number of delegates" presidential contenders are awarded, based on a formula involving the number of supporters for each candidate, the total number of delegates awarded and overall turnout.
The Iowa primaries voting system is complicated enough that back in 2012 before they started using phone apps, it took 3 weeks to report the caucus results, at least in the case of Republicans.
Somewhat buried in the news is this titbid (apparently enabled by the new app, but also causing problems [see end of answer for that])
For the first time, the Iowa Democratic Party reported three sets of results this year: a tally of caucusgoers’ initial candidate preference; vote totals from the “final alignment” after supporters of lower-ranking candidates were able to make a second choice, and the total number of State Delegate Equivalents each candidate received.
A few more details (about the 2020 app) as related on CNN from the users' perspective:
Precinct captains were given a six-digit PIN that they enter into the app, which identifies the precinct captain and allows them to input the results.
Kimberlea Burt Baker, a caucus chair in Fayette County, told CNN that users were required to know their precinct number and PIN to get past the login screen.
From there, the app prompted an "outline or agenda," said Baker, who oversaw caucuses in the Banks Township and Fremont Township.
Users were required to fill out the results in the app and at the end include a picture of the results.
"Take a photo of the signed Caucus Reporting Sheet to send to Iowa State Democratic Party using the campaign button below," the app reads.
The app includes a summary of the "final alignment," showing all the Democratic candidates with their viability percent and number of delegates listed.
Baker also told CNN that the only step that didn't work for her was including the photo with the results.
"I received an error every time I tried to take the picture," said Baker, who submitted her results on the app without a photo.
A rather blurry set of screenshots was also published by CNN
We also know a bit more of how the 2016 Iowa app looked like, since it was shared by the Republicans and Democrats back then. (The 2020 app is not shared.) And also what the problems were with the phone line reporting...
The app will record each precinct's tally, and send the results to party headquarters in Des Moines.
While the app itself is bare-bones and basic — it kind of looks like a calculator — it stands out in what will otherwise be a decidedly low-tech affair. Republicans often cast their ballots on slips of paper, and Democrats count their support for candidates by grouping together in corners at caucus sites.
Microsoft approached Iowa's Republican and Democratic parties with the app idea. The software giant developed the program at no cost as a showcase for its election-reporting technology. [...]
Both parties were quick to sign up for the pitch. (Not all campaigns share the enthusiasm, though: The Bernie Sanders campaign will arm volunteers with its own in-house reporting app to independently keep tabs on results.)
Each precinct will designate one person who will download the app to his or her phone and record the evening's results. Those recording will need to be registered with either the Republican or Democratic Party beforehand, so they can be texted a two-step verification code on caucus night.
On the Republican side, volunteers will enter the precincts' total number of caucus-goers. If each candidate's vote totals don't equal that figure, an error message will pop up and the results won't be recorded. Democrats use a different, percentage-based counting method.
Microsoft says the parties will also be able to guard against reporting errors. They'll be able to set "thresholds for each precinct. We didn't expect a thousand people for this precinct, or we didn't expect two people in this precinct," said Stan Freck, senior director of campaign technology services.
Those settings, Republicans and Microsoft argue, will safeguard against the types of recording errors that sometimes plagued the old system: a simple automated telephone hotline, which volunteers would call to punch in their sites' totals.
That phone hotline was "liable to error — you don't get to confirm anything," said Ryan Frederick, Adair County's Republican chair. "It just goes off into the ether, and you watch the news to see if it was right."
Many caucus volunteers are less tech savvy, and Alex Latcham, who conducts caucus training sessions for the Republican Party, said he has spent a lot of training time just showing people how to download and install apps on their phones.
Microsoft's Freck said that has been the biggest hurdle during the run-up to the caucuses. "It's a fairly simple application," he said in the company's Washington, D.C., offices. "But as always, people are involved. ... There are over 1,800 precincts. So we're going to get precinct chairs and people who are involved that have all different levels of ... tech comfort."
That's a main reason why Microsoft and both parties are doing so many test runs before Feb. 1.
(There a lot of screenshots of the 2016 app in this training presentation, starting around slide 70. As far as I can tell there was no photo step in that one.)
And the human factor was apparently an issue again in 2020. Although the lack of technical transparency was much discussed in technical forums, the issue that caused the delays was apparently not that...
Computer experts and caucus chairs said there was not enough training on using the app before Monday's caucuses, which are chaotic enough as it is.
"It appears in this case that the app was never really tested in a manner which came close to approximating the real mess of an election," Doug Jones, a computer science professor at the University of Iowa and a former caucus precinct leader, told NPR on Tuesday.
"Caucus chairs, in many cases, apparently were attempting to download and install the app on their phones on caucus night," he said. "That's extraordinarily difficult to do that kind of thing under pressure."
Holly Christine Brown, the Asian/Pacific Islander caucus chair for the Iowa Democratic Party, said she was only appointed precinct chair last week and first saw the app on Friday evening.
"We were just given access to the app and told, 'Play around in there a little bit,' and that was about as much training as we got," Brown told NPR's Rachel Martin. "We were able to call in and ask questions, but there was no real training on the app." [...]
Elesha Gayman, the Scott County Democratic chair, said the app was difficult to use for older and younger people alike.
"It was unique; it's not something you can download in the app store," she said. "You actually had to fill out a form. In addition to that, you got a series of PIN numbers. And so, yeah, there was a lot of layers and I think that absolutely mucked it up. Anecdotally, a few of the people I do know who used the app successfully were younger people. But I do know some young people that also had troubles, just so many layers."
Marjie Foster, the Democratic chair of Decatur County, said her caucus "had absolutely no glitches with the app. Our app process worked great. Our chair was very well-prepared. He had trained and tested, and he was on target with it. So we had no issues with the app."
But the app didn't work for Des Moines County Democratic Party Co-Chairman Tom Courtney.
"Things didn't work out right," said Courtney, who said he tried to call in the results for several hours but couldn't get through because the number was "constantly busy."
Instead, Courtney said, he went home and planned to call and report his precinct's results in the morning.
[...] Early Tuesday afternoon, Iowa Secretary of State Paul Pate said in a statement that the accuracy of the vote totals "is much more important than the timeliness of releasing the results. I am glad to hear they have a paper trail for their votes, just as we use paper ballots in all official elections in the State of Iowa. I support [the Iowa Democratic Party] while they take their time and conduct checks and balances to ensure the accuracy and integrity of the votes."
On the other hand, CNN reported that besides some users having interface issues with the app
A Democratic source tells CNN that the issue seems to lie with a major coding error in the app that was discovered once data started flowing into the state party and officials began to see discrepancies in the three data streams as the results started coming.
The source said that it took time for party officials to identify the issue and try to address it, and noted there was not a problem with the raw data being put in by the individual precincts. [...]
The party said it found "inconsistencies" in the reporting of "three sets of results" and is using photos of results along with paper trails to validate the results.
"As part of our investigation, we determined with certainty that the underlying data collected via the app was sound. While the app was recording data accurately, it was reporting out only partial data," Price said in a statement.
To me this suggests inadequate end-to-end testing...