The entire mod is NOT out yet. Part 1 will come out around 21.00 GMT+2 tonight. (ninjaed by Sheridan)
They have uploaded Part 2 so you can download it early, and then when Part 1 comes out start playing immediately.
The Steam Workshop says Part 2 is only 310mb, however it is a 4gb download which turns into a 12gb mod file which can be found here when fully downloaded C:\Program Files (x86)\Steam\steamapps\workshop\content\325610\1381536100