Hello,
In order to display your theme exactly how it is on demo you have to import two files, the DAT and XML.
The DAT will give you all the customizer settings. You’re going to need this plugin to import it:
https://wordpress.org/plugins/customizer-export-import/
The XML will give you the same posts that are on the Demo. I would say it’s optional.
If you have any issues let me know