When you get to the stoplights, the first mess is for Los Alcarrizos, the next one is ??? and the third one is for Manoguayabo. Then you are near Kilometer 9.
Stay to the right and take the off ramp that says Av. Luperon. There might even be a sign that says. Aeropuerto Herrera -> or something like that/ DO NOT GO OVER THE OVERPASS...You have to slide down to the right...I am pretty sure that it is the first right after that third traffic light.
You will be going South.
About one klick to the South you will see the Airport Terminal on your right..It is very obvious.