I should also add that I tried setting up the host machine as a file server using XAMPP (if you are trying to solve the same problem later the forum search function will help you find the thread from which I learned to do this), and it appears that what HFS will do as well. I was able to make the files sharable as an Apache server and viewable by browser over my local network, but unable to get IW5 to download them upon connecting to the match—I got the same error as described in the OP. In this case, in the server config file I pointed the game to either the localhost OR the local IP address of the host machine, and got the same error. In the case of setting the host machine as the file host for a game over the internet, to where should I point the game via the server config file?
I can share the exact contents of my htaccess file and my server config file in a bit.