To enable synchronization between your Treadly app and your Apple Watch, Click Settings > Apple Watch and toggle it on. If you don’t have an Apple watch that is synchronized with your phone, you will not see the Apple Watch feature in the app setting menu.
When you want to use your watch to track your stats, you need to start your workout from the Treadly app on your Apple Watch. When you start your workout from your Apple Watch, it will not start your Treadly as well. Once you start your workout from the watch - start your Treadly simultaneously via your app or handrail.