Flier1K

You're seeing this because you don't have any formatted partitions to install to (the folder you see is the install media, not a target disk). Reboot the VM and select "Disk Utility" from the recovery screen. There you will see multiple disks, including the one you allocated in the Macinabox parameters. Select that disk, the click the "Erase" button to format it. Once complete, you can return to the recovery screen and proceed with the install.