Railworks requires SketchUp Pro 2024 or newer on Windows 10 or 11, 64-bit. macOS is not supported in this release. The STEP engine is a bundled Windows binary and no Mac build of it ships yet, so a Mac install would fail at exactly the step you bought the extension for.
Who this applies to
Anyone checking whether their office install will run the extension before buying or starting a trial.
- SketchUp Make, Shop, and versions before 2024 are not supported.
- Check your version under Help → About SketchUp.
When to contact support
If you are on a supported version and still cannot load, send the exact SketchUp version string from About.