I have been running poser since version 1, so 1,2,3,4,5 and 7.
I have been running it on a mac from os 7, 7.5, 8, 9, to osx 10.4.9
I have never had any problems with zip file or runtime instulations
in osx mac has it's own unzip program a widget that just unpacks it

post poser 5 uses png files so if you have rsr file you use RSRCONV
If you are still running poser 4 or Poser Pro you're in mac os 9 at best
and then you use MACONVERTER

Don't worry about it, just don't make it a .exe