For years, Guffy’s post processor was the PP of choice Fusion 360 users. Earlier this year Don Gamble forked Guffy’s project and made substantial improvements. See this forum topic for Don Gamble’s work.
Note that last October, Fusion 360 made changes in the personal licence version of their software that broke using Guffy’s postprocessor. In particular, it resulted in the lead-screw-driven Z axis being moved too fast. This problem can be mitigated by executing the following g-code once (i.e. the change is persistent).
M203 Z8 ; Limit Z feedrate M500 ; Save the setting to EEPROM
As for driving the MPCNC over USB, there is a Mac version of Repetier-Host. Repetier-Host is the primary way Window’s users driver the MPCNC over USB. Here are the V1 setup instructions for Repetier-Host. Note that I’m not a Mac user, so I’ve never tried the Mac version of Repetier-Host.
I’m not sure how old your students are, but beyond USB control, there are other control solutions that you may want to explore with them. The MPCNC can be controlled wirelessly using a Raspberry PI. Not something I’ve done, but here is a link to some instructions and a firmware image.
Personally I stuck to the SD card, but created a pendant to make setup easier. While my pendant is custom, here is a Thingiverse link to a MPCNC pendant project that provided the knowledge in how to build the pendant.
What age are your students? What are they making?
Edit to clarify: The g-code a post processor generates is independent of the platform/tools used to send the g-code to the control board, so you don’t need to change your post processor if you are using a Mac to send the g-code vs. using the SD card.