https://digilent.com/reference/programmable-logic/guides/installing-vivado-and-vitis
"Open Xilinx's Downloads page in a new tab. Find the section of the page entitled “Vivado Design Suite - HLx Editions - <Version #>”.
You have to go to the 2020.3 tab to find this.
Newer is "Vivado ML Edition". ML shows support so I can't see why HLx would be required? If correct can I suggest Digilent support updates the above page.