For the most stable experience and to avoid "missing library" errors, you should download the latest version from the official Fredo6 listing on SketchUcation troubleshooting a specific error

: Obsolete. Users typically only search for this specific version if they are using very old versions of SketchUp (pre-2017). SketchUp Community 2. Technical Specifications (Current Version)

LibFredo6 Version 6.9 is an outdated shared plugin library for SketchUp developed by Fredo6. While it was once a standard requirement for popular extensions like RoundCorner JointPushPull