I will post here a full collectibles
guide. The dlc has 21 documents, 1 relic, 6 survival caches, and 1 challenge locations. One document collect you automatically during the story, the whole challenge is during the lift drive, so we have in Wicked Vale 28 collectibles locations. You can not all collect on your first visit here, come back after the story!.
All collectibles are immediately saved. When you push the back button on your controller you have an overview for the area where you are. With the Y button you see the challenge. In spoiler is the timeline for the video