Few things to note.
You can create match either on the website OR in the app.
You can’t move anything you created in the app (e.g. the match itself, stages or registration) back to the website (except posting match results).
You can pull your match registrations into another match you’ve created on the device (e.g. created using your own custom match template in the app).
For small matches you can do everything on device and register your shooters as they arrive and checkin to the range. It is not that much more work and then you don’t need to create match on the website. And just post your match results to PractiScore website once match is completed. There are few downsides for that - like no pre-registration and no visibility of the match on the PractiScore website.