Well, you still need Kontakt or Kontakt Player, then you can use Host Automation to assign “Instrument” parameters AND then yes, map Gig Performer widgets to above mentioned host automation.
This is usually true for most Kontakt “Instruments”/Libraries.
As @keyman noted, that “package” is in fact just a library that requires the Kontakt plugin.
NI only sells a few actual plugins (and the best way to get them is to buy one of their Komplete packs, e.g. KOMPLETE 14)
Everything else is typically either an instrument for Kontakt or an ensemble for Reaktor. They also have some patch libraries for their synth plugins (Massive, FM8, etc)
There are also numerous third party instruments for Kontakt out there.