The "Bootable" legacy ISO you've used is in fact not bootable, it relies on CDROM emulation provided by BIOS. VMs don't usually do this sort of emulation. If you set the guest OS to something like ...

Jack Wallen shows you how to do an unattended installation of Linux with the new release of VirtualBox 7.0 to help make your virtual machine deployment even easier. Image: Gorodenkoff/Adobe Stock ...