You may have not changed the default admin profile details inside cyberpanel. The email id by default for username admin is the above stated one. You need to change it there.
The ‘additional step’ of needing to type an email address to be set as admin, either during installation or at first login, is insignificant compared to the amount of confusion this causes.
Well, in Europe, that can be a serious issue and something really expensive due to Data Privacy Policies.
The additional step is worth to take a second and introduce and e-mail.