You can download the forum in a few different ways.
NOTE: If you are using Nuget or WPI, please make sure it's the latest version. As both sites can take a couple of weeks to update to the latest release.
You can find the source on GitHub
And get the latest releases from there too
You can install the forum via the link below
MVC Forum is on the web platform installer to make it easier for you install and get up and running.