I don't see it on the actual site when I check, it's not showing up in my library there either! :(
It doesn't show up seperately, but you can download the Legacy version under the Warmaster edition.
That's stupid as hell Nordic/Whoever ported this. Why couldn't you just make it a separate library item like you did with Darksiders 2?
EDIT: That's not the original version. The original version is 10GB, legacy is 16GB. For reference, warmastered is 22GB. I didn't realise slapping a couple of ambient occlusion effects on and replacing textures with slightly higher-res versions warranted more than doubling the game's size. Still, that also doesn't explain how the "original" version gained an extra 6GB.