I get the same error, and always have:

Registering your LISTSERV password

An invalid response was received from the authentication server. You may want to try logging in again, or
contacting the webmaster.

I guess I just didn't care enough about the web archive interface to bother to get it working.
Maybe it's because I once moved LISTSERV from C: to D: (although I re-define'd it, I believe!)

Should D:\LISTSERV\MAIN be in the path? It isn't.

Maybe I need another copy of LISTSERV\MAIN on drive C:? No, that didn't help.

Maybe placing a copy of LSV into CGI-BIN would help? No.

Maybe a newer wa.exe would work better?
08/05/97  11:15a               154,112 wa.exe
Newer one from the ftp directory for Listserv (wa-intel.exe):
07/21/98  09:47p               111,616 wa.exe

No, that didn't help.
Maybe I need a newer default.wwwtpl? But I'm using an unmodified one from 1.8c:
07/13/97  10:48a                25,446 default.wwwtpl
07/12/97  09:11p                40,582 default.mailtpl
08/19/97  04:36p               908,288 lsv.exe