Zakra comes with more than 60 demo sites. Some of them are premium demos: https://zakratheme.com/demos/.
Premium demo sites use a premium plugin called Companion Addons for Elementor plugin.
So, it requires Companion Addons for Elementor to import the premium demo site.
Install and activate the Companion Addons for the Elementor plugin just like you did for the Zakra Pro plugin: https://docs.themegrill.com/zakra/docs/how-to-install-zakra-pro/
Now, go to Appearance > Demo Importer, and you should be able to import the premium demos.
