As the error messages says, the source site contains items of custom post type and custom taxonomy, not supported on the mother site. Therefore they cannot be imported.
Custom post types and taxonomies are defined by themes or plugins. You will need to identify which theme or plugin defines them and either install them on the mother site as well, or disable them on the source site.
This can be done just for 1 minute, until the import process is over. After that, you can turn the site back, as it was.
Article ID: 140
Category: WP Empire Builder