: Double-click the downloaded .exe file to extract the files. The installer will usually start automatically after extraction; click Install to proceed. Launching in French How to change the language of AutoCAD products - Autodesk

: If you use AutoCAD Mechanical 2021 or Factory Design Utilities , ensure you download the version-specific language pack for that exact toolset. AutoCAD 2021 Language Packs - Autodesk

After installation, you do not need to reinstall the entire software. A new for the French version will be created. Simply launch AutoCAD using the shortcut labeled with "French" or "Français" to see the interface and documentation in that language.