By default, the links will automatically populate in each email that goes out in sequence. You cannot test these individually as this only works when sent out in sequence beginning with the initial email. Each contact receives a unique link to leave their review.
You may use the External Feedback Page URL if you're sending emails from outside of our software. This will link to a page where the customer will enter in all of their information. It is not recommended as the primary source, but is available.