How are you viewing the site?
Phone? Tablet? Laptop? PC?
App? What App? Browser? What browser? Desktop or mobile view?
Your Mobile Nations Passport is how you log on to Mobile Nations sites: webOS Nation, iMore, Connectedly, Android Central, Crackberry, Windows Central and the Mobile Nations Forum (beta).
I believe that in V-Bulletin (the software used to build out the forums) guests can not see attachments, only registered members who are logged in can view attachments. Sounds like you were looking at attachments and being asked to log in.