UPDATED:
#1 just because you have a PK3 in your etmain does not mean it will download to a client. I know that with pk3 map files if you have them in rotation (meaning that they are listed in the map config that is running at the time) the client has to download them. If they are not in the map config there is no reason for them to be downloaded. This I think is your problem. Figured this out in playing around with them for day’s trying to figure out why clients had to download all the PK3 files just to play the one that was running on the serve at the time. Turns out that only the ones that are listed in the map config running at the time have to be downloaded. 
#2 Is your set sv_allowdownload set to 1 in your server config?
In your game, is the GET MISSING FILES FROM SERVER set to yes?
Also in your game, is the USE HTTP/FTP set to yes?
I have tested your link and it works!!
Boils down to you have to tell the server that you want the clients to download this file.
On another note, if servers start doing this (having clients download customized files for their server) can you imagine how many files are going to build up?? :eek:
My suggestion to you is that you put a note with the link to it in your PBSV.CFG, under the PB_SV_TASK, this uses a “SAY” command that will spam it to your server and the client can then decide if they want to use it or not. :chef:
Also as an added note, your sv_dl_maxrate has an upper limit of 25000, watch the server counsel when some one connects (if you get the URL working) and you will see it won’t go over 25000. But this does not effect the URL downloads at all they will come as fast as the URL server will let it.
:drink:[/b]