the list of compatible devices and basic requirement can be found here click to see
Best Answer@Lmyhre Your iPhone 6 is compatible, but your iOS is not. The Fitbit app requires iOS 12.2 or newer. I still use a 6s which supports iOS 13.
Laurie | Maryland
Sense 2, Luxe, Aria 2 | iOS | Mac OS
Take a look at the Fitbit help site for further assistance and information.