The maps from the AP are the important ones.
The folio pack is not strictly necessary, but helpful.
If you want to go the extra mile, it wouldn't hurt to have a few canned wilderness encounter maps for assorted types of terrain: forest, plains, mountain, swamp.
Honestly, though, if you're running on a physical tabletop, a decent plain map grid like the ones from Chessex is ample for random encounters. Scribble a few rocks on, maybe a tree and a creek, call it good.
If you're running using virtual tabletop (VTT) software like Roll20, Maptool, or Fantasy Grounds, it's worth doing some time googling for a selection of decent maps for a variety of different terrain. I made some plains maps a couple years ago which you are welcome to use if you like, either for VTT or printed out for tabletop.
