Answer: plug in the USB cable (unless you have a CR-6 SE). iPhone or iPad - no, they don't run a full OS. Mac - no problem, just download Cura (and Repetier Host if desired, or Chitubox for MSLA), install, and connect the USB cable. I've been printing from MacOS since 2011-ish, and the only platform related problems I've had were due to bugs in some slicers, or one printer firmware that could only read Windows line endings for gcode. If you have a CR-6 SE: then don't connect the USB cable, because you'll probably burn something, just use the SD card instead. Follow the CR-6 SE forums for fixes to the heatbed and how to isolate the 5V line on the USB cable to prevent damage to the printer or computer.