Page 12 of the manual. There is no driver required, but you do need some hardware, and some DAW software on the iOS device.
"US-2x2: You will need a Lightning to USB Camera Adapter1
and an AC adapter (sold separately).2
US-4x4: You will need a Lightning to USB Camera
Adapter.1
1 You must obtain a genuine Apple Lightning to USB
Camera Adapter separately.
2 DC5V TASCAM PS-P520 AC adapter (sold separately)"