Martin,
We have settings for admin approval/activation in two places.
* Under JFBConnect > Configuration > General tab, there is a 'Skip Joomla User Activation' setting. When set to No, JFBConnect should respect the Joomla settings in Global Configuration, even if automatic registration is enabled.
* Under JFBConnect > Profiles, some of the profile plugins like Community Builder have settings regarding activation, so make sure to configure those too if necessary.
Please let us know if you are still having trouble after configuring these two different settings.
-Melissa