I made it through the red maze just about before I ran out of time but I didn't find a key, I went back in and the overhead shot didn't seem to show a key either? Or if it did, I blinked and missed it -maybe that screen could stay up a little longer.
Honestly, with the spooky music and the sounds the ghosts make, I think you could rebrand this as a horror game, less grass and more haunted house or something.