If your DAW does not supports AU (Audio Unit) you can host an AU as a VST with the help of the free KUSHVIEW ELEMENT, this will load like a regular VST plugin in your DAW and let you load an AU, it's simple and fast.
use this direct link to get the last public release which is free: github.com/kushview/Element/releases/download/0.41.1
Plugins which are available in Native OSX Format are:
-VProm 2.0.4 VST AU
-VSDSX 2.0.2 AU
-CLapTrap 1.2.0 AU
-Elastic EL-2.0.0 AU (early January 2021)
Since April 2019 everything I am putting out is cross-platform (MAC and PC) but until I will be able to provide native OSX versions for some of my older plugins, I would like to point you toward some existing workaround that might do the job for you; the tools are free and prove to work fine for a some people.
Some people also use a cheap PC as another external hardware, like your hardware synths, modular systems or effect units, you simply send the MIDI from your Mac DAW and route the audio of the PC soundcard back into your Mac. I recently found a Blog Post by Python Blue that might be useful, it is a detailed How-To for the VLinn version 1.0 that was Windows only, this technique should work with my other VSTs as well.
So what do I need?
You can download the following .pdf instructions to learn how simple it works. Keep in mind that it is a workaround and might not be bug free. At least you can try!