The map, like the clue card, appears to be an important part of the puzzle. However, the fact that it is in pieces in the book counters this hypothesis to some extent, as reconstructing it requires damaging the book (unless you make a photocopy).
According to the Castaneda/Boone solution, the center of the map represents the shape of trees at the treasure location. There are other possibilities. One theory I worked on is derived from the fact that we have a bunch of ARROWS. This may be a way to to bring attention to text containing the digraph RO or its reverse OR (meaning GOLD in French).
The track around the map may be more interesting. It contains 100 spaces. Four horses appear to be walking around the map, all in the same direction. The spacing between horses may be important.
If the spaces can be filled with letters, then horses moving around the map could be a way to select letters to form a text.