If you haven't emailed
support@wolflair.com about this yet, you should do that first.
Second, activating your Hero Lab Classic license number in the Mac version should work the same way as in the Windows version; you only need to worry about the online site if you're buying new game systems or data packages. Once you have activated your license and downloaded your game system(s) within HLC you should see your purchased data packages within the game system(s).