Super Admin – Adding Administrators with Multiple Identities
Successful authentication is required for Administrators to be able to manage subscribers in the new portal. As customers leverage Microsoft Online Services that require an Azure Active Directory (AAD) tenant, Administrators may find themselves in a situation where their email address and the directory address isn't the same.
Refer to the Visual Studio Subscriptions: Super Admin - Multiple Identities
article for details on how can Super Admins differentiate between sign-in and communication addresses.