The http://www.docjava.com site has been hacked in the past. As a result, only SSH clients are permitted into the system.
1. Get an account from Prof. Lyon and use a web start app to get in
2. Or, for a Linux system use ssh to get in, or scp to do your copies.
3. Or, for a Windows/Mac system use Jcterm for ssh and Winscp for file transfers.
If you know of better clients that work, please let me know, particularly if they are shareware, freeware, or GPL.