Community admins are able to choose one or multiple "Default Groups". It means that all the community members will be automatically added to these groups when they log-in for the first time. So, they do not need to join the group manually in order to see the group content inside their home feed.
To add a default group, go to your Admin Panel> from the left menu, click on the Groups app under the App Settings> add the Default Groups in the groups' settings> Update the changes:
