The reason it works as a "guest" is because guests aren't required to migrate information to an SE Account. The reason you get the incorrect POL Pass/ID error is because, it is indeed incorrect. You are supposed to log in with your SE ACCOUNT information, not your POL information.

You mentioned a few years; 2-3 years at best? Or using "few years" to simplify "a long ass time" like 6+? Because if it's the latter, you might not be setting it up properly in the launcher. You will need to login with SE account ID and password.