Answer
The TouchMix-30 Pro features a built-in USB audio interface, so its USB can connect directly to a Mac or Windows computer for multitrack recording with a digital audio workstation (DAW).
The TouchMix-8 and TouchMix-16 do not have a USB audio interface. You can use an external USB audio interface to record a mono or stereo mix from the mains or other analog outputs, or use an external USB storage drive to record the channels as individual tracks for later mixdown on a DAW.