Contact the developer for a compatible, 64-bit version of the screen saver.
Mac OS X v10.6: Unable to use third-party screensaver
When attempting to install, preview, or run a third-party screen saver in Mac OS X v10.6 Snow Leopard on a Mac that has a 64-bit processor, you may see this alert:
"You cannot use the screensaver (NAME) on this computer. Contact the developer of this screen saver for a newer version."