What you need to do if you have taken a dd or real raw image dump of a hard disk:
VBoxManage convertdd windows2019-eval-template.img windows2019.vdi --format VDI
The .img is the raw dd dump and the .vdi is the output file.
--format VDIspecifies to output to .vdi format
If you are in a pinch you can always use qemu-kvm binary and manually specify the .img as your disk and i........