I saw a question on Politics Stack Exchange titled How did Republicans get a majority of governorships and lose the popular vote by almost 3 million votes in 2018?. This made me think that Democratic governors won the popular vote by about as many votes as Hillary Clinton did in 2016. I am not sure if this is a valid way to talk about this for multiple reasons. But, I am curious. I don't think this is a duplicate because it talks about the national vote total, not why or how this result was reached.
Hilary Clinton won the 2016 presidential popular vote by 2,868,686 votes, or by 2.09% according to the FEC.
In terms of the national vote, the Democrats won the 2018 gubernatorial race by a very similar 2,822,073 votes, but as fewer people voted in these elections, this was larger in percentage terms - 3.07%.
I'm not sure whether you can draw many conclusions from this, for reasons you seem to be aware of by your question, and indeed, are explained in some of the answers to the question you've linked to.