First, check whether your domain is registered with Google Domains. You can perform a Whois Lookup to check your current registrar. If you registered your domain name with G Suite, it is likely that you registered the domain with one of G Suite’s other domain host partners. You can only use the Google Domains console to manage domains registered directly with us.
If your domain is registered with Google Domains, also make sure that you are signed in under the correct Google account if you have multiple Google accounts. Check the upper right corner of your browser window to see which account you are logged in with.
If you still see the "You don’t have any domains yet!" message after checking every possible account, contact Google Domains support.