As you will see below, I have successfully installed the application on my compute running x64 version of Windows 8.1. The cause to your problems might be related to the launch condition. For example, right click the setup package and select Run as Administrator. Since the files require to be installed on the system partition, this trick will give access to the installer to do so.
-Windows XP, Windows Vista, Windows 7, Windows 8
-MS Excel 2003/ 2007/ 2010 (32/64 bit) / 2013 (32/64 bit)
Download latest version from: http://doneex.com/index.php?option=com_content&task=section&id=14&Itemid=49