I'm sufffering exactly the exact same issue. I have registered the ring through the control app. But when I get to verify element of the ring the password email combination is never correct. I've double checked the email address is correct and even tried case sensitive permutations. I've reset the password each time and nothing updates. Yes my phone is connected to the internet ;-)

If I go back to the control app to try and register it tells me that the ring is already registered and asks me if I want to change my password.

I'm going round and round and round... but to be honest just think there is a bug somewhere