I've noticed that the 1.04 version available here is the PC version, and the Mac version is still at 1.03. Curious if there's a 1.04 for Mac out there. If not, gotta load up bootcamp!
It's a ren'py game. So, the only difference between Mac, PC and Linux versions is the content of the "/lib/[OS]" folder ; and the .app folder for Mac. The game itself is completely independent of the OS and, as long as you don't push it too much, even independent of the version of ren'py. A game made for ren'py 6.99.12.4.2187 have 99% chance to work with any other ren'py 6.99.12.4.wxyz, and 95% chance to work with any 6.99.12.a.wxyz.
So, if you put the content of the "/game" folder of the 1.04 PC, in the "/game" folder of the 1.03 Mac (remove it's content before), it should work. Obviously, it's better if you already have the 1.03 Mac version, since you don't have to download it twice. If not, you can try the same, but with a different game you already have, that use the same version of ren'py.