Activating an Extension in Cubase

According to user manual Activating an Extension in Cubase is : Select Audio > Extensions, and select the desired extension
But where is the ‘Extension’ under Audio? and why “Make Direct Offline Processing Permanent” is disabled here?

Please help.

Hi,

Do you have any Extension installed?

It seems, there are no Direct Offline Processes on the the selected Audio event. Therefore the menu item is greyed out.