Downloading Penumbra collection for Mac from Desura

[xoagray]

I downloaded the Mac version of this game from Desura. But it seems the files aren't mac files. I would expect the games would be in .dmg format or packaged to load on a Mac, what I got were a bunch of files in a zip folder with .exe files in them.
i downloaded it 3 times to make sure I wasn't hitting the wrong button or something. For some reason, it's not giving me the Mac installers for the full version of the Penumbra collection.

It looks like it's giving me the Windows version of the game, even though I'm hitting the Mac download button. Is there some other way I can get the files? I paid for it via Desura, so I don't know if I can also get it from Frictional's website or something else?

Here's hoping.