Upload via EpicWar link, eg: https://www.epicwar.com/maps/179039/

..or via Hive Workshop link, eg: https://www.hiveworkshop.com/threads/tkok-eastern-kingdom-3-3-0f.146077/

You can then load the map on bnet using: /w lagabuse.com .map Legion TD Mega 3.43
Check the full guide on custom map hosting.