A global administrator register herself as a Nintex administrator. And now has the option to register other administrators by the button Add administrator.

But if she fills in an emailadress and continues with the registration she gets the message:

Oops! Something went wrong.

If the problem persists, contact your support team with the following information:

Unauthorized access exception. Customer Id: xxxxxxxxxx, DateTime: 7/29/2020 10:47:30 AM

Are there any more requirments to a user for adding an administrator?