I get the same error.

Actually it works for me on iOS 15.0 beta 8 and Xcode beta 13.0 beta 5.

There is a video about it from WWDC 2021 called Meet the Screen Time API: https://developer.apple.com/videos/play/wwdc2021/10123/ There are actually 3 APIs (none of them have Screen Time in the name) Managed Settings (https://developer.apple.com/documentation/ManagedSettings) Family Controls (https://developer.apple.com/documentation/familycontrols/) Device Activity (https://developer.apple.com/documentation/deviceactivity/)