https is only available to paid accounts, free accounts do not support it.
you need to remove any references to https.
you also need to set your cloudflare to accept http not https.
if you use wordpress or similar, its the same, change it to use http.
I have reminded admins once again about the root issue that someone elses content is shown.
As for cloudflare and SSL on your root domain, appears you don't use our name servers so we could not possibly change anything.
That being said, on the records we do have there is a cloudflare notation for the root domain, I'm not using cloudflare myself though so not sure that is the missing link in its own, they are just not queried when someone visits your domain.
that was of course before directadmin and a lot has changed since then.I was using CloudFlare+CPanel before and it was running perfectly since I have set it up back then.
Of course, there shouln't be someone elses content showing either, and that part is definitely on us to sort out.
That error would likely be related to the fact that the certificate is only valid for the root domain (though i may actually help with cloudflare to have it enabled as that would allow for some level of encryption between cloudflare and our servers if I'm not entirely mistaken, with cloudflare flexible that is).