Facebook button in registration confirmation page

Stefano,
Sorry for the delayed response.

In the JFBConnect -> Configuration area, there's an option for "Integrate into Joomla Login". If you set that to Top, Bottom, or Both, the social login buttons will be shown on the standard Joomla login page, including the one shown after activation.

I hope that helps, but if not, just let me know.

Thanks,
Alex