I think you're on the same idrive CIC version as my '08. I'm on an Android S8+, but the AUX function is pretty basic - nothing shows on screen other than it stating you're on AUX. So the AUX cable just plugs into the headphone jack and you'd use whatever player on the phone and start the music (Google Play Music).

I don't know anything about connecting via USB but the beauty of AUX is you can also just get a bluetooth dongle to plug into the AUX port and have the car act as a wireless bluetooth speaker. https://www.amazon.com/gp/product/B075WSFTTV

My setup is with that plus a magnetic vent mount for the phone to control the music there and also accessible for GPS maps. Simple and wireless.

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'08 X5 3.0si - Alpine White / Saddle Brown interior
Specs: Sport Pkg, Premium Pkg, Tech Pkg, Comfort Access, Aero Kit, Style 433 staggered 20s on Conti DWS
Mods: Carbon 35 tint, LED angel eyes, GP Thunder 7500k fogs, H&R 20mm/25mm spacers, clear reflectors, gunsmoke-tinted taillights
Coded: Digital speedo, windows/sunroof/tailgate close via keyfob

X5 pics at Flickr