What's the error, and when do you receive the error? I just did this on a Windows server, I'll list the steps I followed - let us know where it goes wrong for you?
Downloaded the MinecraftEdu - World of Humanities - November 2012.zip file.
Unzipped the file.
Copied the Humanities 2012 folder from the formerly zipped file into (on a Windows server) into AppData/Roaming/MinecraftEdu/ServerTool/worlds/savedworlds
Launched MinecraftEdu and started the Server Tool
Clicked "Select Saved World" and chose Humanities 2012
Clicked "Start Server with Selected World"
Caveat: I don't know if that's the 'correct' way to do it, or the easiest way to do it, but it works :)
On a Mac, you'll want to find where the MinecraftEdu folder lives. I'm guessing the rest of the path (ServerTool/worlds/savedworlds) would be the same?
Now that I've gone through all that, I'm wondering if you're not looking to run a server, but just run MinecraftEdu locally, offline, and load the world without connecting to a server. In that case, unstuff/unzip until you can get just the Humanities 2012 folder. Find your MinecraftEdu folder and find the Minecraft folder within it. There should be a "saves" folder, and if you've played other worlds, you'll see those world folders in the "saves" folder. Copy Humanities 2012 folder into the "saves" folder, and the next time you boot MinecraftEdu and choose Single Player, you should see Humanities 2012 as an option?
A lot of explanation - hopefully you'll either find an answer or at least be able to tell me where my suggestions stop working :)