If you upload the zip file of the world with the datapack it wont work. Datapacks only work in the server's main world. The solution is to rename the zip file of the world with the datapack to "world" (or whatever you want), upload that zip file, go to settings on minehut, change the level name to "ul_world" (or ul+whatever you want), save and restart, and then delete the old world folder and the old nether and end folder. After doing this the datapack will work in your world.