The theme demo uses the
AMP for WP plugin for displaying Accelerated Mobile Pages that make your website load faster on mobile devices. To get started install and activate this plugin (the one on the left):
Once this plugin is installed and activated you can proceed to configure it to your liking. The Corporate Pro theme demo uses the Design Three theme which can be selected from AMP → Design → Themes:
More information can be found on the plugin’s WordPress.org page here https://wordpress.org/plugins/accelerated-mobile-pages/.