Skilling runs on Drupal, an open source content management system (CMS) popular in education. Schools from Oxford and Harvard to your local K12 use Drupal. You can see a partial list of institutions running Drupal.
You can download Skilling from Skilling's project page on Drupal.Org. You can also get Skilling with Composer, or a combination of Git and Composer.
Skilling's documentation explains how to install the software on a web server. After you've installed Drupal, of course.
If you want to experiment with Skilling, you can run it on a low-cost shared web host. Reclaimed Hosting is an inexpensive, education-oriented hosting service that can run Skilling.