USB-C on this platform are behind Thunderbolt 3, which is not supported yet. Please avoid using USB-C on this platform, and USB-A(USB3.0) ports should work for you.
Please let me know if you have any question with USB-A ports.
I am trying to test this driver on one of the newest Mac mini. (2018). My problem is that I only have USB-C adapters, and plugging anything USB-C while booting (either the installer or the installed ESXI) gives me a purple screen of death. Plugging the adapter after booting doesn't get it to be recognized. Any tips?