Set up your custom domain
Your new CNAME record has two parts: a domain and a target. Together, the domain and the target values create one record which will enable us to order an SSL certificate for your domain or subdomain.
If adding the entire string with the domain name doesn’t work, try just adding the alphanumeric string (token) before your domain. (If using a subdomain, try as "token.subdomain", and leave off the domain.) For example, Namecheap, Google domains, and Gandi all follow this token-only or token.subdomain pattern.
All registrars look a little bit different, so it might take a minute to figure out how to get yours to work.
This video explains how to setup your DNS records.
This screenshot is what correct DNS records should look like:
Please note, www.yourdomain.com with the “www” prefix will not work by default. If you’d like to have visitors be able to use the “www” prefix in addition to using your domain or subdomain directly, you will have to create a new CNAME record with a domain/host/name of “www” or "www.subdomain" (no quotes) and a target/points to/value of the domain or subdomain you will be using: ie, yourdomain.com or subdomain.domain.com.