This version is required to play "non-player" libraries (often cheaper or niche boutique libraries) and is essential if you want to build your own instruments. According to Westwood Instruments , the Player version does not allow you to edit or build your own instruments. Version History and Compatibility
If you are looking for Kontakt, the best way to acquire it is through the official Native Access portal. Native-Instruments-Kontakt-7.1.5.rar
Using official versions ensures developers are compensated for the thousands of hours spent recording and coding these instruments. How to Get Kontakt Safely This version is required to play "non-player" libraries