Help is here!
Login errors are almost always related to one of two things: (1) security settings, or (2) cookies or improper caching of login data. On iOS, these are both relatively easy to fix.
First, check your security settings. From your home screen, tap on Settings, then Safari. Under Privacy, make sure private browsing is turned off, and accept cookies is set either to "always", or "from visited". If that checks out, then click on the "clear cookies and data" button. That should do it!
Regards,
Jonathan Atkinson
www.ballroomdancers.com