No. While the Apple Watch integrates with Future and can be used during your workouts it isn’t required to use the app.
The benefit of using an Apple watch is that adds another accountability factor to the Future experience. The watch tracks your movements, heart rate, workout length, and calories burned during workouts.
That data is sent to your coach so they can see how hard you’re working and how quickly you recover. Improvements over time indicate you’re getting more fit!
On its own, the watch can also track steps and calories burned throughout the day which can help with weight loss goals.