Hello,
As you can read in the first line of the instructions: "Setting up a WSL virtual machine is deprecated because WSL1 does support only Ubuntu 18.04.".
If you really want to use WSL and you have experience in working with linux virtual machines you could try to setup a WSL2 with ubuntu 20. See here for more information about WSL. But there is no tutorial and no support to do that from our side.
We highly recommend you to use Automatically installed virtual machine based on QEMU. A video on how to setup a development environment using QEMU can be found here.
Best regards,
Nick
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