Start by selecting "Manage" from the main navigation.

The click "Groups"

Click on "Add Group"

Click the "Group Name" field and add a Group Name then click Save.

Success! Click "OK"

Once you have an existing Group click the 3 ellipses/dots to the right of the Group name and select "Configuration"

Click into the "Max capacity" field and enter a number.

Click "Save" and then "OK"