If anybody knows the people who run the ciggaweed custom maps server, please tell them you can't play on it!
When it goes to download the map, it gives you a 404 error. It appears that they have a double slash in the URL to download the maps.
Edit: I included a screen capture of this error in Windows 10 on my laptop, but it was doing the same thing in FreeBSD and Fedora 22 on my desktop.