I haven't tried it in MacOS yet… If you dive into the HDA you might be able to see what the error is. Or if you uncheck the Hide Instant Meshes dialog, maybe the terminal will give you some info.
For what it's worth, mine is now part of the Game Development Toolset up on Github.
I'm hoping to record a video of it todayhttps://github.com/sideeffects/GameDevelopmentToolset/tree/Development
The issue was with having object level scales. I'm going to take a look at it and see if I can take those into consideration, but the easiest solution is to remove those scale values and apply those at the geometry level.
Attached you'll find a file that works with Unity.
Hope this gets you working again