Hello! I use an iPad (pre-Pro – it has a lightning port) with my Focusrite Scarlett 4i4. The 4i4 I think requires a little more power than the 2i2 and below. It was a bit hard to find info on what exactly to buy. I found Focusrite pages telling me I needed a powered USB hub, but in the end all I needed was this:
Plug your iPad power cable into the female lightning port on this adapter. Plug in that power cable and keep it plugged in while you use your iPad with your audio interface. If it’s not plugged in your iPad will not have enough power to run your Focusrite. Now plug your interface (Focusrite) into the larger USB female port and your interface should power on.
Since you have an iPad Pro I think it has a USB C port, not a lightning port like mine does. In that case, you probably can use this adapter: Apple USB-C Digital AV Multiport Adapter
I also think this cheaper one would work:
Amazon let me return the adapters/cables that were wrong and I wasn’t charged for shipping.
Hope that helps.