Train Fitness supports the Apple Watch Series 4 and newer. If you are having troubles installing the app on your Apple Watch, the first thing to do is to confirm your watch is supported.
How to confirm if your watch is supported:
How to confirm if your watch is updated to watchOS 10.0+ :
Once you have confirmed your watch model is supported, you will need to next confirm your watch is running the watchOS 10.0 or newer. This is the minimum operating system Train Fitness can run on.
You can find your Watch Operating System by following the below steps:
Open the Apple Watch app on your iPhone.
Tap the My Watch tab, then tap General > About.
If your watchOS version is below 10.0, you must update your watch before using Train Fitness.