When you have setup a connection to AAD and limit access to users based on a AD group, all you need to do is send them the URL to access. However if you would like to limit the subscription they see in their dashboard you need to change settings on the user (after his first login), so it would be helpfull to alerts the admin(s) that a new user has logged on to the site, so the admins know of a new user and can modify his rights