As Rast Sound is a third party developer for Kontakt (like many others), adding a library from the “add library” function in Kontakt is not possible. One should use the files tab in order to add and play third party libraries.
From the files tab you have to locate your target library (Mideast Vocals in this case) and find the folder structure where Kontakt instruments will appear on the bottom window. Simply double click or carry any instrument to start playing it.
We recommend you to collect all third party libraries in the same folder for easy navigation. This way, your third party Kontakt libraries will be organised & ready to go.