You would need an audio interface with a minimum of 2 inputs. You would also need a cable adapter to go from 1/8" (3.5mm) stereo, to 2 XLR left/right male.
Another possible option. You say the app won't let you export, which many may not, but the audio is still on the ipad. You may be able to extract the files from the ipad by connecting to the computer via usb. You would most likey have to set the ipad to also be a USB storage device, and you can do that in while connected to the pc, in itunes, in the device properties.