Walk across the street and into the garage, go up the escalator and look to your left, there is a board outside the booth that will tell you either a spot number or which aisle to choose from. If your name isn't on the board, walk up to the desk and they will take care of you. The last time I was at MCO in January, there was a sign at the Hertz counter inside that said for all Gold Plus members to go to the booth in the garage.
It appears that Hertz' last website and app update removed the section that informed you if you had Gold Canopy access with your rental. I just checked my upcoming rental at MCO and it's not on there. It was there a few weeks ago at least on the website, I don't use the app unless I'm actually travelling.