Did you perchance mean Windows "Health and Fitness App"?
https://forums.windowscentral.com/e...-health-fitness%2F9wzdncrfj3q5&token=lK7WFYJN
Or maybe "Microsoft Sync App"?
Download Microsoft Band Sync app for Windows from Official Microsoft Download Center
AFAIK there isn't a version of the Health App that runs on 8.1 or 10...phones only (right?).
-Matt