Sorry about that. With the new v5.2 release of JFBConnect, we cleaned up the settings a little bit and it looks like we missed that bit of documentation.
To let the user go through a form-based registration, you simply need to disable the "Enable Automatic Registration" setting. When disabled, a user account won't automatically be created and you can show extra fields to the user. You'll still have control over whether the username, password and email fields are shown though, so that you can provide a more streamlined registration process.
You should leave the "Registration Component" set for JFBConnect. We don't currently support using the Community Builder registration flow, though that's something we're investigating.
I hope that helps, but if not, let me know.
Thanks,
Alex