Im on mac and it said the file cant be opened, so I tried the "chmod a+x" thing on the nwjs file in the MacOS folder. When I opened it, the nwjs just crashed.
I'm unfortunately not sure. Anything known about getting the game to work on Mac OS is detailed in the !zMAC USERS PLEASE READ.txt file, so if it's not in there, there's not much else I can offer