I do recall that at one point I had to re-login into the classic app. During that process, I had to choose “New Account”, but then was able to log in with my new Samsung account. It didn’t create a new account.
You might also end up with an extra “Location” in your account. There are numerous discussions regarding how to remove the extra empty location after setting the correct Default location.
Don’t panic if it looks like everything is gone from your account. Search the forums for the instructions as many have already done the account migration.
Lots of good advice in this thread