If you are considering deployment of the Receiver in your workplace (as opposed to installation on just your machine), have a look at the Citrix Receiver deployment how-to in the Ubuntu for the Enterprise wiki. You will need you will need to have libxaw7 installed, but no wfcmgr (the Citrix ICA Client executable) and OpenMotif. If you are using the XenApp web plugin, which is NOT exactly the same as the ICA Client, you should also see this page: CitrixXenAppPlugin. Instructions for current/recent versions are at CitrixICAClientHowTo. The instructions on this page are for old versions of Ubuntu/ICA. The Citrix ICA Client (Citrix Receiver) allows access to remote Windows sessions run on a Citrix server.