These are often public domain or shared by enthusiasts who no longer use the hardware.

If you cannot find a reliable S900 link, these free libraries offer similar high-quality workstation sounds:

If you own a and have the full version of Kontakt (not just the free player), you can create your own library. This is 100% legal for personal use.

store provides legitimate expansion packs for physical hardware rather than Kontakt-ready formats. Conclusion

Launch Kontakt as a standalone application or as a VST plugin inside your DAW.