Copy the MechanicalSample.addin file into one of these folders :
C:/Program Files/Autodesk/Inventor 2024/Bin/Addins.
C:/Users/(Name)/AppData/Roaming/Autodesk/Inventor2024/Addins.
C:/ProgramData/Autodesk/Inventor2024/Addins. (If not available, the Addins folder can be created here)
Another Inventor® version may also be present