I did more research,and I think I have an answer, Voter Gravity uses only people who have voted in the primary and general elections in the last 8 years. A lot of Trump’s support is from people who are angry to be voting for the first time, or have not voted in all the elections so they would be eliminated in the Voter Gravity surveys. That is why the numbers seem not to match anything.
We just need to help people register and Especially the Fed up new young voters. Trump needs to promote voter registration! A couple of his 35 need to get on this. :)