I don’t see anything about running this in the browser on that page. Is there a place to demo this somewhere?
You can then click on the "Startup link" labeled "click here" for the OS and CPU architecture you want to try out.
riscv64 Linux 4.15.0 (Fedora 29) X Window -> https://bellard.org/jslinux/vm.html?cpu=riscv64&url=https://...