Metal Performance Shaders ?????
i was not allowed to download an app which identifies objects and I got an error message saying it wasn’t possible cause I don’t have a metal performance shader???
Metal Performance Shaders are a framework used by application developers.
https://developer.apple.com/documentation/metalperformanceshaders
It sounds like you're trying to download an app from someplace other than the App Store. If so, that would not be a good idea.