When you have a branded domain from outside of Rebrandly, you will need to configure its DNS records to point to Rebrandly's IP address.
Do not change settings for a domain you're using for a live website. This domain should only be used for creating branded links.
We recommend searching for your domain registrar's support documentation for editing DNS records before you begin. The location of the DNS settings will be different for each provider, and some even have templates to make the setup easier.
To set up the DNS:
You can now add the domain to Rebrandly, if you haven't already.