I use Tapatalk for several fishing forums. I tried logging out of my account and relogging in with no issues. I logged in manually so use your exact username and password. Perhaps it might be a bug or something as Tapatalk had issues in the past for some people.
Also certain forums may deny access depending on the IP. I doubt this is the case but I have had it happen to me in the past.
Sent from a smartphone with Tapatalk installed on it.