To find your Facebook reviews URL visit your facebook page and click on your reviews tab (it may be behind the 'More' dropdown).
Next, copy the URL in the bar which you can paste into your Feedback Settings in the loyalBe dashboard.
Save your settings and that's it done!
Tip: the facebook review URL is just your facebook page with "/reviews" at the end.
E.g.
https://www.facebook.com/YOUR_PAGE_NAME/reviews