Help with installing Toilet Survival Map

There are a few different possible issues here. If you're on single player, make sure the file is unzipped and placed in your saves folder, then you can access it from the singleplayer menu (it will be in the list of saves, not by creating a new world). In multiplayer, you load it into the server and either rename the file "world" and replace the existing world folder, or edit your server.properties to indicate the new name. Additionally, make sure command blocks are enabled in server.properties. Finally, in multiplayer it is somewhat common for players to spawn at the wrong coordinates for maps, in which case loading the map in singleplayer to find the correct coordinates is the easier solution. Then you can just teleport or fly to those coordinates in the multiplayer version.

Have you checked to make sure you're loading the world in the correct version of the game? I've accidentally done that several times lol. The only other fix I can think of is to read the instructions on the map description itself to see if there's anything you have to do before it'll work.