You need a promotions page to redirect people to after they click your pop up and give you their info. That’s the deal: They give you their info in exchange for access to your promotions.
You can offer anything from $5-10 off, 50% off their second day rental, or just send them to their packages page.
Create a page in BCN with that mentions your promo or use a page you currently have.
Either way you will need the url of this page for the next step