Hi ​@Andrea Vincenzo Braga, welcome to the Sonos Community!

I’m sorry to hear that you’re having issues setting up your Sonos Arc and Sub. Currently, we’re aware of an issue where the “sign-in as system owner” message shows up, blocking the screen to add a new product. The workaround would be to reset the app (or delete and reinstall), however since you’ve already done that, I would recommend trying on a different device with the Sonos app installed.

If another device doesn’t work, or you don’t have access to one, then I would suggest you contact our support team to troubleshoot this further with them. They have the necessary tools available to look into your system and see what’s going wrong.

I hope this helps!