Given dimensions (A>B):
4 x AxA
18 x AxB
18 x BxA

(3)
(11)
(10)
(5)

Note: Under the Menu->Document outline section of the PDF, there is some metadata-like string of characters. For this and all other pdfs that may appear in this hunt, such information is not relevant to the puzzle and may be ignored.

Hints

We have no idea what is going on in this puzzle.

Note the dimensions of each page in the pdf, you should notice a pattern.
There is a way to assemble the pages together to form a (2D) shape that may remind you of something that has 40 spaces.

40 Spaces