For this, in addition of GroupJive, you need CB Activity and CB Auto Actions.

Actually, if you just install and publish the CB Activity and CB Auto-Action plugins, the "Follow" and "Like" buttons will appear in GroupJive.

To install: go to Community Builder / Plugins Management / Install & Update then in left on "Community Builder plugins", then simply click "Install for CB Auto-actions and then on CB Activity. Check that they installed successfully on top of screen each time. Then click "Close" button at top, and search for them in the plugins management, and click on the "Published" X to become a green checkmark "√". CB auto-actions has all system auto-actions that will be processing those buttons.

You can then if you wish further configure details of CB Activity.

No need to touch CB Auto-Actions configuration.

Nothing needed for CB Activity system actions.

But make sure that you have all CB, CB activity and CB Auto-action extensions published/enabled. in particular, search for "CB" and "Community Builder" in Joomla's Extensions / Plugins.

I just tested clicking "Follow" becoming "Follwing" on the group, so that works.

But by default, there is no activity logged or displayed for following/unfollowing a group (albeit there is an activity status for following or not following). But for joining a group, there is an activity displayed (but not for unjoining).