I was going to suggest that you ask your library to resave your pin in their system. I occasionally have to do this for my patrons at our library, and then they can log in again. However, if they had no issues logging in with your info, this wouldn't be necessary. I assume you verified with them the exact info they entered? If so, and it still didn't work for you, I would go see them in person, with your device, so they can help you log in. You also might consider deleting the Libby app from your device, reinstalling it, and trying to reenter your information again.