[command line instructions ahead…]
Vagrant, a virtual machine manager written in Ruby, is an option for Windows 8; it provides a WSL-like environment (Windows Subsystem for Linux, a Windows 10 feature).
Vagrant can use Docker, Hyper-V or VirtualBox as a virtual machine provider, in case you already have one of those installed. If not, the easiest tool to use for setup is Chocolatey; once Chocolatey is installed, the command choco install -y virtualbox vagrant will install both Vagrant and VirtualBox.
From there, follow the Vagrant Project Setup guide to install an Ubuntu VM, e.g. vagrant init hashicorp/bionic64 (or bionic32 if your Windows 8 install is 32-bit).
Beginners Guide to Install Discourse on Windows 10 for Development should be usable from there (I hope).