You're definitely added to the group, and you should be able to send emails to it from your email address as you have been doing. If you'd like to view and/or post from the group's web interface (which is the provided link), you'll need a Google account. I believe you can create one with your existing email here: https://accounts.google.com/signupwithoutgmail
You need to manually add your character's name to the subject line of your sims. So for you, you'd put something like: Cadet Dugoras - The Title of My Sim
I think I've sorted your forum issue, but if you have any problems, please let me know.