If you are a website owner that is having difficulty accessing your DirectAdmin control panel after enabling Cloudflare, you must be sure you are accessing your DirectAdmin control panel via its IP or via a subdomain that is not proxied by Cloudflare. At this time, Cloudflare does not proxy the port over which DirectAdmin runs.
If you are a hosting provider and use DirectAdmin as your control panel, then you can integrate Cloudflare using the Custom API. At this time, Cloudflare does not have a DirectAdmin plugin. Apply to be a Certified Partner here.