Changes since SOA version
IXFR is a zone transfer request that returns changes since a specific SOA version. Enter the SOA version to request changes since then.
Not an apex domain
The domain c93646b319604df084f86e69213b98d1.pacloudflare.com is not the root of its zone.
Instead, try zone transfer on pacloudflare.com .
Instead, try zone transfer on pacloudflare.com .