Shopify Facebook app - share product button unavailable by Maxence Lacroix

Hi everyone !

In the documentation of the Facebook Shopify App and on some Facebook shops, I can see that it exists a share button under each product of the Facebook e-shop. However, this button doesn't appear on my shop. I checked everywhere to find the setting which would allow me to add it but was not able to find it.

Can anyone help me here? 

Thanks a lot :)

Cheers,

Max