Thats difficult to explain just by typing like that.
I will try though
I use social locker premium plugin by bizpanda from codecanyon for that purpose
I create landing page using profit builder
I create two step optin button using thrive leads
I put social locker content inside the thrive lead form
I put thrive leads shortcode on the desired place where i want the button to appear
Hope this make sense.
I will try to make a video when i will be free. Lot of works assigned right now
Is the Social Locker you are referring to this one: https://codecanyon.net/item/social-locker-for-wordpress/3667715