.. The first portcullis

The two discs must be the solution. Henrik can just go and grab the moon disc from the wolf.

It is too far up, even for Henrik. You would need to get on that ledge.

Have you explored the area thoroughly?

Explore behind the raven statue.

Yup, Tove's way in.

Henrik can pull the bars wide apart. After that Tove gets in.

Now Tove can climb up the wall and grab the sun disc held by the stag's antlers.

Tove can now insert them into the slots to open the first portcullis. Now, open the second one.