1) Are you running on a Mac? If you are, email
[email protected] with details of your purchase and your FG website username. Steam DLC isn't supported on a Mac.
2) If you're running on a PC, perform the following: Login to the Steam app on your PC. Start up Fantasy Grounds and go to the settings screen - make sure "Check Steam for DLC" is selected. Run an update. This should download the module.
You won't see the module as a campaign. You need to start a PFRPG campaign and then go to Library -> Modules and activate the module Then the information will appear as tabs at the bottom of the story, maps, NPCs, etc. screens.
Hope this gets you on track!
Oh, and welcome to Fantasy Grounds! :)