Slightly disappointed by Penumbra Overture

[KvRaiden]

I bought the Penumbra Collectors Pack off Steam. The problem is when I went to my games library, Penumbra Overture was the only one that launched. Both Black Plague and Requiem do not. When I try to play it, It says validating files, then I stops and says that the Steam server is busy. This cant be the case, because I've been trying all day and night for a week. Can someone please help.
(I use a Mac)