The Florida law requires a felon to go to the local sheriff's office in Florida and be photographed and fingerprinted.
Many other states and cities have similar laws, with varying wording and time periods. There was a U.S. Supreme Court case about these kinds of laws in 1957, when somebody who had been convicted of forgery traveled to Los Angeles and failed to comply with the Los Angeles registration ordinance..
https://en.wikipedia.org/wiki/Lambert_v._California
Trump's lawyers probably forgot about criminal registration laws until now. Because Trump travels a lot, after they read my post, they'll have to get busy researching which states and cities have such laws. You can be certain that, when Trump's opponents read this, they will get busy. I wonder if Wisconsin or Milwaukee has that kind of law. I don't imagine Milwaukee officials are very happy with Trump
right now.
Most convicted criminals don't travel as much as Trump, and these laws are not a big concern for most felons.