Invalid email

Hello,
I sent a message to support about this issue but just received an automated response telling me to ask on here (possibly because it's a Sunday).

This is my original musescore account which I created using my Facebook account, but as it doesn't have an email linked to it (except the auto-generated one based on my username), I can't change my username or add an actual email or password.
To avoid this problem, I tried to create a new account and sign up with my Google account and outlook email (both have the same email address) and an error message popped up telling me the address was invalid.

Any help would be much appreciated. Thanks