It doesn't serve the Airport Station, use the MIA Mover instead. Cross the street from the bus stop going towards the garage, there is an elevator to the left that will take you right there, level 3.
The 133 is a free shuttle that connects the Airport Terminal with the Hialeah Market/Airport Tri-Rail station. Some trips serve the Tri-Rail/Metrorail Transfer Station on NW 79 Street as well.