"Unfortunately, Windows Phone has a much smaller number of users compared to Android and iOS. This means that the market is relatively small. It is always a good idea to check the future possibilities of a platform before buying a phone.
At the movement the app is still available in the Windows Store but will no longer be updated by the company as stated above. This is another bad news for Windows Phone users and fans who use the app. Now since the company has decided to stop updating the app, the users are advised to download Fitbit app which is a Universal App for Windows 10.
If you are interested you can download the app from the below link.