This build uses more than the maximum structures that the defaul Ark settings. If you are playing a single-player game or the server you are playing on doesn't let you finish it, you can use the cage part (back of the raft) 3x2 instead of 3x3, which will reduce 7 pieces. Also, you can replace the window frames and windows with only window frames or walls. The rails on the cage to prevent the raptors from escaping can be eliminated, or use only one-story-tall walls on the back. Finally, the three ceilings I did use to make a second floor on the side of the raft can be eliminated too.

About the mats, doing a fast count, the build will need:
1 Raft
44 Walls
9 Ramps
5 doors
2 rails
1 ladder
3 sloped walls
21 ceilings