The supported OSs are grouped into types. If you
want to install something very unusual that is not listed, select the Other type.
Depending on your selection,
If you prefer to install the OS, you can disable the unattended guest operating system install feature by selecting Skip Unattended Installation. In that case, the selected ISO image is mounted automatically on the DVD drive of the new VM and you must install the OS from there.
Not all images support unattended installation.