Hello, @webpat,
I have checked your provided site and this is what I see on your site: https://postimg.cc/0KP3PpDY it has the error. Please first make sure that your server requirements must meet the theme and plugins requirements like: https://imgbb.com/VBscvWg and for that contact your hosting provider.
And then Please try to deactivate and then reactivate the theme again with the same purchase code and then try to import the demo on your site. I hope your issue will be resolved.
Otherwise, please share your site WP Admin and CPanel or FTP Logins in the private content area of this topic as listed below, so that I will check and help you out accordingly.
WP Admin URL:
WP Admin Username:
WP Admin Password:
Cpanel Admin URL:
Cpanel Admin Username:
Cpanel Admin Password:
FTP Login Host:
FTP Login User:
FTP Login Password:
FTP Login Port:
And you can share the screenshots here via these sites: https://postimages.org/ https://imgbb.com/
Regards 8Themes Team.