Audiobus: Use your music apps together.
What is Audiobus? — Audiobus is an award-winning music app for iPhone and iPad which lets you use your other music apps together. Chain effects on your favourite synth, run the output of apps or Audio Units into an app like GarageBand or Loopy, or select a different audio interface output for each app. Route MIDI between apps — drive a synth from a MIDI sequencer, or add an arpeggiator to your MIDI keyboard — or sync with your external MIDI gear. And control your entire setup from a MIDI controller.
Download on the App StoreAudiobus is the app that makes the rest of your setup better.
iTunes Store (not iOS 11 upgraded)
Anyone else who hasn't upgraded yet experiencing the iTunes Store freaking out? It's not accepting my payment information or letting me update my apps. Is it that time to bite the bullet and upgrade already? 
Comments
The App Store has issues from time to time, I'd keep trying until it starts working for you again.
@InfoCheck yeah It's definitely messed up for me before but it's really weird right now, kinda scared me. Thanks!
its kind of the opposite for me payment wise, I normally buy ITunes cards because I dont really want my debit card involved. When I try to redeem an ITunes card on IOS11 theres always some kinda of snag, so I do it on my old Ipad 2 and theres no problems. I can buy apps on my Air2 afterwards but redeeming cards work a LOT better on the old store for me.
After restarting my iPad a second time it seems to be working right now. Glad I didn't go to 11 yet. Gonna hold out.
It has nothing to do with iOS 11. The AppStore has problems every once in a while. In this latest round of issues I was trying to get a subscription on iOS 11 but nothing. Had to go to an old iPad on iOS 9.3.5 to get it to work. (Unlike you and it probably was more random luck than anything else to be honest))
Nothing to do with the OS more to do with the apple servers or something.