Most modern NI software is managed through Native Access . You will typically need to create a free account there to register and activate your free player.
Sites like FileHippo sometimes host older installers like version 5.03 for Windows users. Key Features kontakt-5-player-free-download-softfiler
Works as a standalone app or as a plugin (VST, AU, AAX) in your DAW. Most modern NI software is managed through Native Access