Hi ​@Ala 

Welcome to the Sonos Community!

Sorry to hear of this issue you are having with being prompted to sign in as the system owner.

If you are using the same email to log in to the app as you have used to log in and post here, then you are using the wrong email, as there are no Sonos speakers registered to the email that you are using here.

If you have another email that you use, please try it instead.

Please note that you can sign in to the Sonos app using any Sonos-registered email address, but your system is registered to a particular email, and logging in with any other will work, but you will see that message.

If you can’t figure out which email your system is registered to, you will need to register it to a different email. To do this, please go to User icon » Sign Out and once done, go to Settings Icon » General Settings » Transfer System Ownership to start the process.

I hope this helps.