You should stop searching for a shady "Autodesk AutoCAD Plant 3D 2019 free download." Instead, pursue these ethical, safe routes:

Sync your Piping and Instrumentation Diagrams directly with the 3D model to ensure data consistency.

If you need AutoCAD Plant 3D for legitimate purposes, consider:

Autodesk AutoCAD Plant 3D 2019: Features, System Requirements, and Access

While individuals are rarely sued, companies found using unlicensed Autodesk software face fines up to plus legal fees. Autodesk actively uses telemetry (even in old versions) to audit large firms.

If you are specifically looking for the 2019 release, it introduced several workflow improvements: Plant 3D Toolset in Autodesk AutoCAD | Features