How to use VMDK image file for VM

I’m trying to install HomeAssistant in a VirtualBox VM. I downloaded the VMDK image file. This image file ends in vmdk.sz. When I try to create the VM hard disk from the image, VirtualBox won’t accept this image file because it doesn’t end in vmdk. What do I do with this vmdk.sz file? Do I just remove the sz extention so that it ends in vmdk? Does the sz file need to be extracted? Odd that this important detail is not in the download page.

SOLVED: I found a link somewhere else on the internet about how to use the sz file in VM applications. The sz file is a compressed file. For the VM images you need to extract the actual image file from the sz file. For the image sz files for use in RPi applications evidently the Etcher program can handle the extract when flashing to the SD card.