In case you get "Error load data from..." messages when installing dummy data, this means that the import from external files is not allowed on the server.
Please enable allow_url_fopen on the server using one of the following methods:
1) edit .htaccess file and add line:
php_value allow_url_fopen On
2) edit php.ini file and add line:
allow_url_fopen = On;
3) Contact your hosting provider.
In case you still have any issues, please provide your website details in the support ticket:
1) website url and Wordpress username/password
2) FTP details: FTP hostname, username and password
3) Direct link to PHPMyadmin tool (or your hosting Cpanel credentials).