This page gives you information about admin settings of BuddyPress Auto Join Groups

Settings ScreenShot:

Settings:

 Currently, plugin offer only one setting i.e. When to apply group lists. This setting allows site admin to control when the group lists groups will add to the user’s group list.

1. User account activation: If enabled, All the matching group lists groups will automatically get added to the user’s group list when their account gets activated.
2. On profile update: If enabled, All the matching group lists groups will automatically get added to the user’s group list when his/her profile gets updated.
3. On member type change: If enabled, All the matching group lists groups will automatically get added to the user’s group lists when his/her member type changed.