What is a “Sonos 5 app”?

There isn't a specific "Sonos 5 app" that I'm aware of. It's possible you might be referring to the Sonos app, which is used to control Sonos speakers and audio systems. Sonos periodically releases updates and new versions of their app, so "Sonos 5 app" could refer to a hypothetical version released in the future.

thank you for a useless response.  I bought 4 rooms of equipment ro play my music.  When I get what I paid for, I will be happy.  Please try not to be so pompous.  

I don’t know if you are a Sonos Employee but if you had something worthwhile to help make my system more than a lot of paper weights now would be the time. Consider it a challenge. CEO Spencer of Sonos needs all the help he can get. Should have sold to Amazon a long time ago

Sonos employees are identified by the forum software, @jgatie is not one. 

So far I haven’t seen anything useful..what I am looking for is the app that allows my musc library to play through the Sonos system. Thanks for correcting my error of calling it Sonos 5.  Give me the correct name as if that will help. It used to be a simple matter of updating under the manage menu bar. Now there is no action no matter what you call the last few new and improved Sonos updates.