Zend Server Windows Installer
Guard Loader PHP Extension (runtime component of Zend Guard)
When Zend Server 8.0 was released, Guard 7 was not yet ready so we had no runtime for PHP 5.5 + 5.6 and thus, Zend Server installer did not include a Guard Loader module.
Once Zend Server 8.5 is released, it will include Guard Loader module for installation.
If you are installing Zend Server 8.0 and need Guard Loader component, you should install it manually within Zend Server 8.0 using the instructions in the readme.txt of the Guard Loader for PHP 5.5 / 5.6 stand-alone package.