This is an HTML template. To get started you need only Browser to run HTML files. Better upload files to the web server and run the site there.
If the template is opened from the local file system, some functions may not work. For example, functions that required PHP – Instagram, Twitter, Contact Form.
To customize the template you can edit CSS and HTML files. Also if you are a developer, there are available source files SCSS, JS (ES6) and HTML (Nunjucks). All used plugins added from npm.
For each page available blank CSS file for your customizations. See it here –