It's not called the Storyteller's Guide, it's called the Companion. Make an account on the world of darkness website, then download it once you've logged in. It's a free PDF. Also anything with the Storyteller's Vault logo on the front (you'll see these on DriveThruRPG, so pay attention to the covers) is homebrew stuff.

However, the Companion doesn't have anything about Koldunism in it. The closest we might get is for some of that stuff to be done as rituals or powers in the upcoming Blood Sigils book, which is a book that's been announced that will have new Blood Sorcery stuff in...