I tried to scan the QR code on my controller but it said "unavailable device number"?

That error message normally indicates that the controller has not yet connected to the internet. The controller MUST have a live internet connection to work with the app. We recommend a hardwire connection from the controller to the router. Check the internet connection (small network symbol displayed on the main page) and then contact tech support (support@trolmaster.eu) if you are still unable to scan the code after the internet connection has been verified.