I don’t think you can set up Sonos without the app 

regards

Simon

@Victor87 What music streaming services do you use? Do you use an iPhone or Android phone?

The Arc should be connected to the TV by the supplied HDMI cable (on the ARC u ), When you tune the TV to a music station it should play through the system. Or am I not understanding your question?

I use Amazon music and Apple Music (I have an iPhone)
And the era 300 will work with the TV if the arc is connected to TV?

I read that the era 300 won’t connect to TV.

Thank you all for reply’s 

Add your Amazon and Apple Music accounts to the Sonos app.

https://support.sonos.com/en-us/article/add-a-music-service-to-sonos

After that, you can use the Amazon or Apple Music app to play music to the Arc, either through your mobile device, or an app on your TV or streamer.  Note, if streaming through the TV or streamer device, you will not get much audio in the surrounds.  If using a mobile device, if you set music sources to Full in the Sonos settings, you will get full volume from surrounds.

The Arc will connect to the TV’s HDMI ARC port. 
 

You bond the Sub to the Arc by following these instructions:
https://support.sonos.com/en-us/article/set-up-your-sonos-sub
 

You bond the Era 300s as surrounds to the Arc by following these instructions:
https://support.sonos.com/en-us/article/add-surround-speakers-to-a-sonos-home-theater

The Arc + Sub + Era 300s will create a 7.1.4 home theater setup.

You can use AirPlay to play music from Amazon Music or Apple Music directly from your iPhone to the Arc setup.

Love you all. 
Cheers