iPad MIDI routing from other apps

I want to use other iPad apps to input MIDI into Dorico. I have AUM for MIDI routing and a handful of other apps that generate MIDI (I mostly want to use MIDI Guitar 2). I can get Dorico to read my MIDI controller, but I can’t find enough documentation about MIDI setup to figure out how to get other apps inside the iPad to talk to Dorico. Any tips?