Go here to activate your key. If you already own the game skip to the last image (right click an image and select open in new tab if its too small to read)
Hit next until you get to this screen and enter you key.
Right click the game once its installed and got to properties. You could play the original version but only if you want to see how fare the The homestead Invasion has come.
Click on the Beta tab. In the drop down select The Homestead Invasion beta, and it should install the 0.2.0 version!
After that give it a try.