I find Aldiko is the best Android reader, both in terms of working as a reader, and working with calibre. I've tried pretty much all of them, but I don't think I'll use anything but Aldiko again.
I got it working just fine with calibre's content server, but I don't know what this authentication thing you're asking about is.
I just turned on calibre's content server, then in Aldiko created a custom catalog with the address being:
Code:
ip.of.content.server:port/stanza
I did use a custom port for my server, but I can't imagine that would make any difference, as long as the one in the server's settings and the one in Aldiko match, and it's not blocked by your firewall or router or anything.
But it never asked for any kind of authentication, so I'm not sure how to help you further.