Your Apple Watch is compatible! Check out how do I connect my Apple Watch to Fiit.
If you have a Versa 3, 2, 1, Versa Lite, Iconic or a Sense Fitbit watch, you can connect to the Fiit app. You will need to check your screen size and software are compatible. Take a look at How to connect your Fitbit to Fit
Fiit is also compatible with 25 other fitness trackers (and counting!).
If you want to track reps during strength training classes, you'll need the Fiit device which counts reps, as well as heart rate and calorie burn. Heart rate-only fitness trackers do not track reps.