Hey there @moririn welcome to the community!
An email is indeed required - This requirement is in place because the email address serves as a unique identifier within Auth0. The primary reason for this is that the email address is a globally unique identifier that can be easily used to contact the user (e.g., for password resets, multi-factor authentication, or other communications).
https://community.auth0.com/t/importing-user-profiles-that-do-not-have-an-email-attribute/113889