It's means, that Php version on the server what you using greater, then magento extension allow. So you can't install it through magento connect. I'm using the trick with this site: http://freegento.com/ddl-magento-extension.php So you should insert the extension key and submit you will get archive with extension that you could extract in your project. Hope it will help you! !important that using this way you will not be able to update this extension through magento connect manager. And also I could be additional issues, because developers tested it only: from PHP version >= 5.2.0 and <= 6.0.0.