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 rev6-2001-41d0-a-1c2c--42-3.mail-out.rqsco.cloud is not the root of its zone.
Instead, try zone transfer on rqsco.cloud .
Instead, try zone transfer on rqsco.cloud .