"Point a subdomain named ferrondemo of your domain name (for example, ferrondemo.example.com) to either: CNAME demo.ferron.sh or A 194.110.4.223"
This is really strange and make my Spidey sense tingle. If the goal is to just point your domain to this server it should not require DNS auth. Just HTTP is fine. DNS sure if you want optimize reverse proxy, because that would be also possible to do via http auth for every subdomain separately. If you just need some www server quickly pointing your domain to some other dude domain is not the way to go.
This feels weird.