Can you quote the exact message you’re getting? Have you tried with a dedicated IRC client rather than using the freenode web client (which I assume is what you’ve tried to use, since that’s what we link in the above linked document)?
The MetaBrainz IRC channels are only on the freenode network, not on IRCnet or other networks.
If it doesn’t help to connect to freenode through another IRC client. I’d redirect you to read https://freenode.net/kb/answer/chat but without more information to go on, I don’t think there’s much I can do to help you. Consider contacting freenode’s support at support@freenode.net and maybe they’ll be able to assist you more.