This is not shown on the map

 If you are going south through Jaco, the road curves to the left. There will be a large sign for the Jaco Fiesta on the left. Turn Right passing the Municipality building. You come to a bridge. In another 600 meters you pass a second smaller bridge. The first street past the bridge is Calle Mora, then Soda Hildago (restaurant) then the Arenal Pacifica Hotel, then Calle Hildago. Turn right (there's a sign for Cabinas Stefano on the corner) and you'll end up at the beach where you can only turn left. 400 meters more and your in front of the Hotel Catalina.

This is the pink route

If you pass all the exits from the hiway into Jaco, then you'll turn right past the gas station. Then take your first right, then your first left (there's a sign for Cabinas Stefano on the corner) .