While you can still download older versions of Citrix Receiver, new features and enhancements will be released for Citrix Workspace app. Beginning August 2018, Citrix Receiver will be replaced by Citrix Workspace app.
Citrix Receivers Citrix Receiver Client for MAC OS X 10.6 Snow Leopard and up including OS X 10.8 Mavericks Citrix Receiver Client for MAC OS X 10.5 Leopard and below Citrix Receiver Cleanup Utlility for Windows.