When logged out, https://spreadfirefox.authstage.mozilla.com/node/1862 has: "No public posts in this group. You must register or login and become a member in order to post messages, and view any private posts." See screenshot.
This instance is the message for moderated/invite only groups
@Mary Is there anything that needs to be done here ? Paul
Yes - can you please change it to "log in"?