Use your own domain for links
On the paid plan, your organization can put its links on its own domain. One domain is included, and you can buy more slots. Go to your organization's settings, open Domains, and add the domain you want to use.
Pointing it at Referr
Referr shows a DNS record to add where you manage your domain: a CNAME pointing at domains.referr.fyi. Once it's in place, Referr checks it and sets up the certificate. Your campaigns' website links then work on your domain, and you can make short links there to anywhere: a store page, a trailer, a sign-up form.
Still stuck? Ask in Referr's Discord server, or write to support@referr.fyi.