No, you don’t have to install anything else if you don’t want to. The provider is doing its best to make its games accessible to a wider audience, so the compatibility with all mobile devices isn’t surprising. You can pick a device powered by iOS, Android, or Windows, including Windows phones. As for the difference between the desktop version, it’s totally absent, while the version for mobiles is optimized and adjustable to mobile screens. However, you can install a mobile app if your operator offers this option.