I am having the same problem, after a fresh install using the installer (this is the first time I'm running KSP on a Mac) when I launch the game it starts the freezes with the message "Loading Asset Bundle Definitions"
I haven't done anything else than a fresh install.
The logs are here: https://pastebin.com/4V9Q9jR0
It seems that KSP cannot access some files like "/Applications/KSP_osx/GameData/Squad/squadcore.ksp", the files do exist: "-rwxr-xr-x 1 root admin 3.2M Oct 5 22:11 /Applications/KSP_osx/GameData/Squad/squadcore.ksp" it might be a permissions problem
My system is:
OS: Mac OS X 10.12.6
CPU: Intel(R) Core(TM) i7-7567U CPU @ 3.50GHz (4)
RAM: 16384
GPU: Intel(R) Iris(TM) Graphics 650 (1536MB)
SM: 41 (OpenGL 4.1 INTEL-10.25.17)
RT Formats: ARGB32, Depth, ARGBHalf, Shadowmap, RGB565, ARGB4444, ARGB1555, Default, ARGB2101010, DefaultHDR, ARGBFloat, RGFloat, RGHalf, RFloat, RHalf, R8, ARGBInt, RGInt, RInt, RGB111110Float