
The top sketch has a small curved face line. I did a new sketch, using the side curve to get the left end of the top profile to align. Loft from it to the inclined line in the side sketch, with the top face curve as centre line rail.

Then a new Loft from the long black curve to the bottom curved edge of the previous body. Hide the inclined body.

Loft from bottom face curve to top face curve, and tangent both selections.

Stitch the 3 bodies together. Then with the top fillet outline curve, trim this body.
You now have the dummy floor and the top faces, to create the wall sections
I used 6 wall profiles in 3 lofts to save Fusion getting to confused.


Created the side walls with top and bottom body edges for rails. All 4 sections thickened to 2 mm, and 2 of the sections did combine with top plate, but the back one fails.

As none of my dimensions would be suitable for you, using your dimensions where you can. As said, I ended up manipulating the canvasses to get this close so they are no longer original either.
Happy to answer questions.
Might help