Try Transmit, its a ftp client.
Panic - Shockingly Good Mac Software.
there is also Fetch and Captian FTP. if an iT department is telling you to use classic mac, i believe they are saying to use os9, which you could in Tiger and below in a "classic enviroment", or an actual os9 mac. which would mean that they would want you to use Fetch most likely, if Transmit cant do it in os X, go to a PC and see if you can log in with the same settings the iT department gave you. i like transmit because it supports a few tricky FTP sites by a simple pull down menu.
hope this helps.
Panic - Shockingly Good Mac Software.
there is also Fetch and Captian FTP. if an iT department is telling you to use classic mac, i believe they are saying to use os9, which you could in Tiger and below in a "classic enviroment", or an actual os9 mac. which would mean that they would want you to use Fetch most likely, if Transmit cant do it in os X, go to a PC and see if you can log in with the same settings the iT department gave you. i like transmit because it supports a few tricky FTP sites by a simple pull down menu.
hope this helps.