I am attaching picture of the user manual.  As you can see in Step 4, parts 9 and 11 make up the side of the shed.  Parts 3, 4 and 1,2 make up the back.  The illustrations show that the sides and back are flush at the ends. However, the height of part 9 is 980mm and the height part 11 is 553mm.  These go together to make side of the shed at a total length of 1533mm.  The height of parts 3 and 4 are 531mm and the heights of parts 1 and 2 are 980mm for a total length of the back of 1511mm.  So the back and sides are off by 22mm.  These will not be flush together on the ends.  So is the extra 22mm go on the top or on the bottom?  The illustrations show they are the same length and there is not extra 22mm sticking out.

In conclusion, is the extra 22mm difference in the sides and back go on the top or on the bottom?