MapleStory does not natively support Macs at this time. This means you cannot download and install the game on your macOS operating system..
However, MapleStory is available on NVIDIA’s game streaming service GeForce NOW. Using this service, you can play MapleStory on your Mac via streaming over the internet.
For detailed information on GeForce NOW and how to access MapleStory, please refer to:
How to play MapleStory through GeForce NOW