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 9091f516df3b45ae3ba357a3ed7e31.mail.outlook.com is not the root of its zone.
Instead, try zone transfer on mail.outlook.com .
Instead, try zone transfer on mail.outlook.com .