Translated post since forums are English only.
An account was created in azure AD. The administrator used a custom domain name. Now the password is not remembered.
However, the password reset function was not set up, and now there is no way to go in.
Tip: I ’m sorry I ca n’t reset your password because you have n’t registered for password reset.
If you are unable to log in, you must contact your administrator to reset your password. Once you are able to log in again, sign up for Self Service Password Reset to ensure that you can reset your password later. If your organization does not have other administrators, contact support.