Meditation is a feature for Count.It PRO users. If you are the Captain/Admin for your group you will see the option on your PRO Admin --> Group Profile page, allowing you to add or remove activities from your group challenges.
PRO groups can log Meditation in two ways:
Logging their meditation via their fitness tracking app. As per this help article, the following trackers support meditation logging: Apple Health, Google Fit, Fitbit, Garmin, and RunKeeper.