Search for trash guides and servarr. Both have websites that are detailed in how to set up all of the arrs apps in what ever fashion you want. I think both have Discord servers too.

Could you set a ‘password’ on the uploads? So the server will only accept and start the upload if the password is present. The password is a passphrase to make it easy to type in.

Depends on your stance on risk since WatchTower has to run as privileged