Where is ObiSoftbody.unitypackage?

[KBTIT_]

The QuickstartGuide_softbody.pdf contains the following information.

1.- Include the Obi package in your project. Right click in the project window, "Import
Package" → "Custom Package", then select ObiSoftbody.unitypackage.

But ObiSoftbody.unitypackage is not in my project.