There's a problem with the symlinks in the Mac App bundle. Instead of proper symlinks, these are plain files containing the symlink target as text. Apparently, this can occur when creating the App bundle on Windows. See this issue for more information: https://github.com/nwjs/nw.js/issues/6606
I was able to create a working App bundle by pasting the Resources folder into this nwjs App bundle downloaded here: https://dl.nwjs.io/v0.46.2/nwjs-v0.46.2-osx-x64.zip. For some reason the game is running slow in fullscreen mode, but other that that it seems to be working well.
I actualy think I just came across why this is and how to fix it https://github.com/golang/go/issues/24057 this issue gives some information on the distinction between TAR and ZIP but to summarise it seems that ZIP support for symlinks is weak and TAR handles them by default I recommend you just switch over to storing the app in TAR and seeing if it helps
this might also help but you likely already read it https://itch.io/docs/itch/integrating/compatibility-policy.html
Best of luck :)