If the library says “full version Kontakt required,” that means:
Approximately 21.2 GB in its full, uncompressed version.
NK STAGE is a specialized stage piano library for the Kontakt sampler, developed by Kollection KEYS. It is designed primarily for live performances, particularly within gospel and contemporary worship contexts, offering a high-quality selection of acoustic and electric pianos. Overview of NK STAGE Full Version
The legitimate source is usually the developer’s website or an authorized reseller like:
I'm assuming you're looking for information related to a specific music production tool or resource. Here's what I found: