Do you mean while you're trying to download the DMG from the FTP site or when you launch the training room client the patch takes forever?
If it's the latter, the training room patch server is kind of overloaded sometimes, it'll get around to finishing eventually.
Manga @ Triumph
"Meanwhile In The Halls Of Titan"...Titan Network Working To Save City Of Heroes
Save Paragon City! Efforts Coordination
No, I mean the .dmg doesn't even finish
Send a support ticket via help.ncsoft.com - this sounds like a connection issue, and they'll be able to help you find the cause and hopefully fix it.
Manga @ Triumph
"Meanwhile In The Halls Of Titan"...Titan Network Working To Save City Of Heroes
Save Paragon City! Efforts Coordination
Okay, I must have tried more than thirty times, but each time I attempt to download the test server, it never fully downloads. As the download time reaches 3 or 4 seconds left, it stops and slowly digresses. Any help?