User login only on one multisite

@therabidmonk. It is possible to prevent users to access sites that are not part of. AAM always had this functionality available as part of Access Policies https://aamportal.com/reference/json-access-policy/resource-action/site.

However, considering the fact that we had an elevated interest in this feature recently, we’ve baked it as part of AAM core settings https://aamportal.com/reference/advanced-access-manager/setting/non-member-access-restriction. By toggling the “Non-member access restricting” option, users that are not part of the site will not have access to it.