Not being a Mac user either, the only input that comes to mind is that when I download software the download page has downloads specifically for Windows or Mac. So, I suppose that you would have to download the Mac version. The installer, and I'm sure, many other aspects of the application are custom for the Mac machine and operating system. Question would be, would the activation code you have for the Windows version work with the Mac version? You will probably have to work with the customer service people to transfer you activation code.
Snow Leopard is a Apple operating system. Same as Windows Pro or Windows Home, etc.