Offending command on provided Postal.ini is: GameFilmScale = 1.000000

Delete the above and the game launches (providing you have renamed "res/levels/postal plus realms.ini" to "res/levels/postal_plus_realms.ini").
Then, according to Snoopium, fails to load res/levels/single/easy/ehome.rlm (if Player has selected Easy Campaign) and reverts back to Main Menu, though path and file are in place.

I have also tried to load the Demo and Postal quits while complaining that the file may be missing or corrupt or I don't have the priviliges (lol wrong OS I suppose :P) to open it (say on "res/demos/default1.dmo", though it's also in place) while postal-mos hits 100% cpu throttle and I have to break it on tasks.

Hope the above helps. Perhaps still easiest way would be just to just share the resources and check them from your side too, or just rip them directly from a win/pc installation I suppose.