Usage This setting is used to determine whether a user is an Office 365 / Azure AD user in your organizational directory or not e.g. when a user attempts to sign into your website manually, change his or her email address or password or when the plugin tries to retrieve an Office 365 profile image instead of the WordPress avatar (depending on the installed plugin edition).
To see your default domain you can navigate to the Azure Portal Azure Active Directory Custom domain names. and find the your default (cloud-only) O365 domain e.g. mycompany.onmicrosoft.com.
Only fill out if you have not added your own custom domain(s) to Microsoft Office 365 or if both domain users and cloud-only users should be able to sign into your website using the plugin.
Default value empty.