Home assistant VDI file downloads as hassos_ova-5.10.vdi.xz

Installation
1

I am trying to install Home Assistant on virtualbox.

I download the VDI file and it is a .xz file
hassos_ova-5.10.vdi.xz

How do I get it into the correct format? or are the instruction on the Home Assistant website no good.

2

https://www.google.com/search?q=xz+file