(https://id.fedoraproject.org)
Nothing to Authenticate
You will be redirected to this service when an application requires authentication against your Fedora Account
This is the single login from fedora you had to sighn up add accounts.fedoraproject.org. You need the alias and the pw from there.
I do use gnome and I saved the login as keyring. This way you not have to log in all the time.