Mac OS Download Page To download the 16.206 Client for Mac OS X click here.     (those who have upgraded to macOS Mojave or above  MUST install 16.115 or greater) To download the 12.1 Client for Mac OS X click here. To download the 11 Client for Mac OS X click here. To download the 10 Client for Mac OS X click here. To download the 9 Client for Mac OS X click here. To download the 8.1 Client for Mac OS 9 click here. Once the installation is complete click here. When the Login screen appears, simply enter your user ID and password and click Login.            For more information about the 12.0 Client for Mac OS X click here. Visit the FirstClass web site to download international clients.