Because "AutoCAD 2009" and "AutoCAD Plant 3D 2010" are significantly outdated, they are no longer supported by Autodesk.
: The Autodesk Account portal typically only provides downloads for the current version plus three years back (e.g., 2027–2024). AutoCAD Plant 3D 2009 Download
The Genesis of a Digital Blueprint: AutoCAD Plant 3D’s 2009 Launch Because "AutoCAD 2009" and "AutoCAD Plant 3D 2010"