You are right, you must create users in fop2 in order to login. When I say that you must check your credentials, if using FreePBX/Elastix you can check the users that fop2 will see/allow by running the autoconfig-users-freepbx.sh script. That way is simple to check if your extension/pass is the one fop2 will accept, in Elastix run:
/etc/asterisk/fop2/autoconfig-users-freepbx.sh
If you do not have any users created, then the list won't have any "user=" lines. Running this script will also give you an idea on how to configure things by hand when needed, or how to check for permissions or groups settings.
Best regards,
