This app is only an extension for the "Shift Scheduler App".
to create an account for free and mange your working shifts directly over this PWA App (app that does not need to be installed). Or ask a friend that use this app to give you the Calendar ID and Friend's Pass.
If you have a calendar ID and a friends password you will able to see all shifts from your friends directly on the home screen of your phone.
This app has the same functionality as the PWA app but with a home widget to see the next shifts directly on the home screen.