At the settings tab of the group page, same as the lesson page, you will be able to see various sections that will allow you to edit the settings on how the group will interact with the user.
The first section to be talked about will be the Display and Content Option where you can control the look and feel of the Course Preview and optional content settings.
From here, you can enable or disable the following:
The second Section will be the Group Access Setting, you can control the timing and the way the group you have published can be accessed. The following options are the access modes that you have available in this section: