That domain have cloudflares name severs set already, though since the IP of the server has changed you need to login to the account there and update the A record for that domain. The IP for your server is: 198.91.81.12
With domains bought elsewhere you set the name severs at the place where you bought it, it was never something you set in cPanel either. With cPanel there was however an integration for cloudflare, this is not available for DirectAdmin as there is no one currently developed, but with increased user base for DA hopefully it may come in the future. That is for either DA or cloudflares developers to decide on however.