First, make sure you have Node.js installed. There are many ways to install Node.js.
Use homebrew. See https://brew.sh to install homebrew.
Download Node.js directly. See this downloads page: https://nodejs.org/en/download/.
You have many options. If you're using Linux, I trust you can figure this one out.
You can use the package.json file to install all of the dependent libraries. Use the command npm install to automatically install your dependencies.
You should use the most recent version of npm. Run npm install -g npm to update to the most recent version.
Sometimes this module will cause installation to fail. Try talking to someone on the team about it.
The project is compiled from pug, sass, and other sources into html and css using the gulp build system.
Use gulp build to 'compile' the project into the files. The build files will appear in the html folder. This folder is not part of the source control. Do not try to add it.
When working on the project, you may find it useful to use the gulp watch command to automatically rebuild the site as you make changes.