Facebook Init is not loaded

Hi,
Thanks for the plugin ??
However, it’s not working, having the message : “Facebook Init is not loaded. Check that you are not running any blocking software or that you have tracking protection turned off if you use Firefox”. Same thing with other browsers.

Our site url is @ domain/dev/
I think it’s a configuration issue, related to app domains. We tried to set the domain & domain/dev but…
Could you please indicate what we must indicate in this field ?