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 and mindfulness in several ways:
Logging meditation directly via one of the supported fitness tracking apps: As per this help article, Count.It syncs directly with Apple Health, Google Fit, Fitbit, Garmin, Strava, and RunKeeper.
Logging meditation in a meditation app (Calm, Insight timer, Headspace, etc.), and then connecting that app to one of the supported apps. (See further details below.)
Connecting to a meditation-only app: While Count.It does not connect directly to meditation-specific apps, most of these apps DO sync with Apple Health and/or Google Fit. So, a user can connect their meditation app to either Apple Health or Google Fit, and Count.It will get the data automatically. Here are some relevant links: