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 25F2ACC2-874C-11E9-9AD1-764C6F05B595._domainkey.hospital.uncu.edu.ar is not the root of its zone.
Instead, try zone transfer on hospital.uncu.edu.ar .
Instead, try zone transfer on hospital.uncu.edu.ar .