Please read our documentation – http://www.8theme.com/demo/docs/royal/#!/installation_upgrade
To avoid problems with demo content import you must be sure that file_get_contents() function is enabled in the server configuration.
Firstly go to Theme Options > Import/Export, press Install base demo content button to install products, categories, posts, projects, some pages. Only after that you’ll be able to install other theme versions correctly. You can install demo page in Theme Options > Import/Export, select needed version and click “Install version” button.
Feel free to ask if you have any other questions.