If I recall, when you click LOG IN and then you enter an email address that doesn’t have an account associated with it, it automatically starts taking you through the account creation steps. Instead it should just error in my opinion “invalid credentials” or something along those lines.
Phone numbers need to be unique per account.This is why the number can’t be verified because you’re trying to create a new account with a one that is already in use with another account.
This is my understanding of it all - just the app trying to be too clever 