Hello,
Thank you for purchasing our theme and for reaching us.
Please, make sure you have checked all the server requirements before the installation – https://xstore.helpscoutdocs.com/article/60-xstore-theme-requirements
Then go to install plugins via Appearance > Install plugins and activate required and recommended plugins
Read more – https://xstore.helpscoutdocs.com/article/34-demo-content
Also, the Core plugin can be installed via FTP.
If you need help with this, provide temporary wp-admin and FTP access in the Private Content area.
Regards