forced fb login in wordpress

I want to create a private community with a double check for the new members! The first is that they can only fb login and the second I have to approve them! The first can be done with an fb login and with a plugin to approve the members..but after this they will have to pay to interact with the content! I tried with plugin paid membership pro to restrict some pages, but when I create a fake user and i go to the site from incognito mode the pages for an unknown reason are visible! Can someone help me how I can make all this work? I want the member to fb login, then approve him then he pays! I dont know if it needs some code to be written or it can be done with plugins that I do not know that they exist! If you can help me to solve this and make this system work i would be really grateful!