You can install Windows via Boot Camp on up to even the 2020 Macs. It just has to be a Mac without the M1 chip. I installed Windows on my 2020 MacBook Pro (non-M1), and while BeamNG doesn't run well, it does run.
The guy could also just install Linux on his Mac, which is free to do so & then play BeamNG through Steam using Proton
What Sithhy said is a good proposition, because making beamng work on mac will require way too much effort from the devs compared to what they'll get from that. So you're gonna need to find a workaround.