Can't create a role - no 'ReaderExtensions Invoke'

I am trying to use reader extensions in ES2 (and basically that is all I need it for) .

I read in 'Configuring Authorization for LiveCycle Reader Extensions ES' in Tour de Livecycle that I need to create a role to assign to a user and that  role  must have ReaderExtensions Invoke permissions among others. Makes sense. But when I go to add it I can't find the ReaderExtensions Invoke  permission. What could the problem be?

Note that I have PERM_READER_EXTENSIONS_WEB_APPLICATION , for example.

And I have a local credential for Reader Extensions installed.

(and , it is pretty obvious) a very new user.

Help!