Your question made me curious, so I spent the day doing a little investigating. The immediate bad news is that the last distributed app that works on macOS is 2.1.1, a 32-bit binary from 2013. The 2.2 app from last April is 64-bit but blows up as soon as you run it. There's been no new ready-to-run binaries (for any platform) for almost a year; I'd say the project is still very much in development rather than a product.
I had not made it to this point so that's why I asked here first, figured someone might know a bit more than me.
That said, if you can run 32-bit software it's worth a try. If you've upgraded to Catalina you will have to build your own from source. If you already have Xcode/HomeBrew/MacPorts installed you can do as I did and muddle your way to a working app (I used the Yosemite build instructions as a guide). If you're not familiar with everything I just said you may want to stop now.
I am running Catalina. I recall seeing info about Xcode/Homebrew/MacPorts but did not pursue. While I enjoy using my MB Air I'm not well versed in "building" a working app. I have a couple of Win laptops that would make suitable DRM donors.
The IC-R8600 is plug and play on macOS. You set the USB port you want to use to IF out in settings and plug it in. On Catalina the app does not know how to ask for permission to use the USB audio interface, but if you run it from Terminal then Terminal will ask and it works. One caveat: by the time I figured all this out there were no DRM broadcasts to be found, but I was able to demodulate AM and FM signals without any problem.
Nice to know about the 8600 and macOS.
I'd say that if you value your time you should just buy one of the many cheap DRM receivers available - if there were any!