Overdrive "Account Cannot be Verified", on Fire Tablet 7

Hi all,

I'm trying to help my sister with her Fire Tablet 7, and she says she can't get into her Overdrive App because she gets the message "Account Cannot be Verified".

Without me seeing her Fire, I can't figure it out. I have a tablet also, but I have not run into this issue, so far;)

Does anyone know what to tell her to do to get back into her Overdrive?

Thank you much, Abby;)