I’ve been struggling to get this working, your non working link helped me!!
for anyone else struggling
go to the facebook developer site for the app
got to facebook login settings
set Valid OAuth redirect URIs to the following format
{yoursite}/wp-content/plugins/wordpress-social-login/hybridauth/?hauth_done=Facebook
so for mdbootstrap it is as per the facebook warning
https://mdbootstrap.com/wp-content/plugins/wordpress-social-login/hybridauth/?hauth_done=Facebook
