Create the sign-up form in Klaviyo (Klaviyo forms are embedded by their form ID) and paste the ID into Klaviyo - Newsletter Form Key on the Klaviyo card. As long as the Public Key is also saved, Sprwt loads Klaviyo's form script on every customer-facing page (not in the admin) and a Sign Up for our Newsletter button in the site footer opens the form. Leave the field empty if you prefer Sprwt's own Email Newsletter Popup Form or a Mailerlite form.