Reverse DNS working on Free Account

Currently, we are using Free PLAN. As per Reverse DNS Topics it will only implemented on enterprise PLAN. However, we create the site i.e. (X is my IP Pool) and its done successfully. The purposed for the creation is to created PTR record for my email Server. But we are confuse that in free plan how can i able to create site name with reverse lookup name (X is my IP Pool)?

You need to coordinate with the party who holds the IP allocation from the RIR. This is normally your service provider. They likely already host a zone covering that IP space and can create the required entry for your host.

If Cloudflare only offers reverse zones to Enterprise customers (which appears to be correct, as far as I can determine), it sounds like you either need an Enterprise plan with Cloudflare, or you need to use another DNS solution to host your reverse zone.

Strange thing is that in free plan i create new site with name (x.x.x is my pool reverse three octat) and successfully created without any issue. My question is how it created without any issue