What he means is that you can install and run the Unity Editor on any platform, create the game there (on your Mac) and test it in the editor, but once you are ready to create a build for Windows 8 store for testing / submission, you can only do this on Windows 8.
Ah. Okay I think I got it. So I can actually start on a windows 8 game on mac but in order to actually finish it or build it to actually be used or played by others it must be done through Windows 8 using visual studio and the. Right? I appreciate all the help Thanks everyone