Business Feature Requests

I am trying to begin using the app with my work on a Mac in Scrivener. Until now I have happily copied and pasted chapters in and out of PWA. Now I am told this method cannot be guaranteed safety so I have to begin using the app. My problem is that I cannot access any Scrivener files in my Mac. When I go to File and Upload, the files are all greyed out and not available. Can someone please help me? It will need to be a person who is up with using Scrivener on a Mac computer. Mine is up today with Mac OS Monterey 12.2 on a 2020 machine. Please advise what I need to do.