How can i get the "Stuffed" Achivement?

I've been trying to install this game to try it out before playing Mind of Marlo, but instead of installing the game, the game's "install" button on the Steam Store page just relinks me to the game page. Could I get some help with this?

Nothing is downloaded when installing the game.

Once you selected three items, how do you start the documentary?

One of the best characters in gaming history. Let's get a game for Boris!