I think there's some confusion between AppleTalk and AFP.
See the File Services Admin Guide 10.5
p. 66 "AppleTalk Support
AFP service no longer supports AppleTalk as a client connection method. Although
AppleTalk clients can see AFP servers in the Chooser, they must use TCP/IP to connect
to these servers.
For more information, see “Mac OS X Clients” on page 80 and “Connecting to the AFP
Server from Mac OS 8 and Mac OS 9 Clients” on page 83. "
http://www.apple.com/server/macosx/resources/
At the very least, connect using the server's IP address.
There's nothing requiring you to connect as the/an admin.