I just bought a home with surround sound installed in the ceiling. I've got 7 speakers inside and 2 speakers outside. No receiver; just a bunch of blue wires coming from the wall

I don't want to spend a ton of money but I would like to be able to used the speakers for basic things like playing music from my phone, maybe hook the tv up to it for football games.

Any recommendations? Do I need a 7.2 or a 9.2? Best place to buy? Used ok? Thanks I'm advance. Apologies if wrong forum

9 channel with a second zone for outside speakers.
Denon or Yamaha. They have one for every budget.
Don't be afraid of accessories for less.
Denon comes with a "sonus" clone system called HEOS that will work with main receiver, include sonos like app and be expandable with sonos like speakers for any room with no wires and independent control.