To access the source code and doing the initial build you only need a relatively modern Linux-based operating system such as Ubuntu, Debian or Fedora. If you are using Ubuntu then please use at least the 20.04 LTS release as that combination is tested most frequently. You can use a more recent version or another system if you want to, as our build system is using bitbake, so it will bootstrap and prepare most of the build dependencies separately from whatever your host system provides.
Follow the documentation All Scenarios OS - Quick Build — All Scenarios OS 0.1.99 documentation to prepare your system, get the source code, build an image for a virtual machine and boot it.
Please share your experience by commenting below.