Apple Watch devices and apps are compatible with iPhone only.
These apps are accessed/managed in the Watch app on iPhone.
You can find detailed information from Apple here.
How to Install:
When you install the iOS app on your iPhone, the app is automatically added to your watch. It will be listed in Installed On Apple Watch.
If not installed, it's listed in Available Apps. Tap Install to add to your watch.
To remove from your watch, tap Name then Show on Apple Watch.
What you can do:
View Health Stats on-screen and on your watch.
Use watch as a Remote to play, stop, rewind videos.
Open watch app, then open video on iPhone or computer.
Track & View Workout Data:
Information is sent to Apple's Health & Fitness apps.
You can track workouts, view stats, and share your activity.
To track data: Tap Start before and End Workout when you're done.
To send data to other devices (iPad): Sign-In to your account is iOS.
Access to Data & Troubleshooting:
To track/view health stats, you must allow access to all requested data.
The first time you use the app, you’ll be prompted to allow access.
You can also enable access in the Health app on iPhone.
Enable access on Apple Watch:
The first time you use the app:
Enable access in Health App:
If you don't see Heart Rate or Calories Burned on your watch or the video:
Enable access to data in Health app