Trouble with new sign-up

Can't get my client's correct e-mail address to take for a new sign up. Need to use their e-mail instead of mine so they have access to everything if someone else takes over form creation after me.

Giving me an error that I have to input a valid e-mail address, even though the e-mail address is, indeed, valid.

How do we get them signed up?

As per checking, there is already an account with the email address prairiegritsports@gmail.com. If you forgot the password, you can request for a reset password by following this guide: How-to-reset-the-password