After setting Aster, connect directly to your Office account.
Please note that:
your registration email for Aster must be the same as for your Office account
you must have an Office administrator account to access to following rights:
If you don't have an Office administrator account, you have the following options:
Create an Aster account with an Office Admin account, sign in to Microsoft via Aster as detailed above, then validate the rights for the members of your organisation;
Manage your group rights directly from Microsoft Azure: https://docs.microsoft.com/en-us/azure/active-directory/fundamentals/active-directory-manage-groups