Hi @othmane
Citrix extension is currently being internally tested. We do not offer the full documentation just yet, so I would not try to install it just yet.
Having said that, your error message revealed a bug that will get fixed 
The “LoadString(141)” is actually this:
It simply indicates that you do not have currently a Citrix Receiver installed on your machine.
Stay tuned for the Stable release of this functionality
Anil_G
Nidhi_Gupta1