it is correct, you must have "Amnesia Fortnight 2017" https://store.steampowered.com/app/631780/ in your library prior to activating this package. This package is just a bunch of videos that are technically just like DLC to the "Amnesia Fortnight 2017" series app that is like a base game.

Edit: I'm not sure is it intended to be like this, but this is how it set up currently and there is nothing wrong at Steamgifts.
Same deal with the 2014 video package: https://www.steamgifts.com/giveaway/mltEe/amnesia-fortnight-2014