Mac OS Download Page To download the 10.0 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 10.0 Client for Mac OS X click here. For more information about the 8.1 Client for Mac OS 9 click here. Visit the FirstClass web site to download international clients. NOTE: If the installer for First Class shows a message that the client is locked.  Trash the application and restart the installer.  You will not lose settings or information. Contact technology for addtional help.