How much fabric is needed in this instructional?
The instructions you've posted call for "two 43" x 65" pieces of fabric." While there are a wide variation of fabric widths available, the standard US widths are (approximately) 45" and 60". As this piece easily fits into a length of 45" fabric (which is often actually closer to 43"), it stands to reason that the pattern is calling for the more common 45" width.

Therefore, you need the called-for 7 1/4 yards of 45" fabric, in an appropriate material (heavy for outdoor use, any for an indoor play tent).

Note that you could also purchase 60" fabric for this project, but you'll have more left over than if you used 45" fabric; patterns that can use either size typically won't call out the width specifically, or will give different yardages for both. Patterns calling for 60" fabric specifically will be explicit about the width, as these patterns generally include pieces that won't fit easily or at all on a 45" wide piece of fabric.