Looks like some of the plugins failed to install. Please try again. If this issue persists, please manually install the failing plugins and come back to this step to import the theme demo data.
When I try to install via XML, I get an error message as well:
error (0)
Please check out the link below for the system requirements in you need in order to import demo data. If you are not sure whether or not your server support this, contact your host.