You must have the base version of AutoCAD 2023 already installed on your computer before you can apply a language pack.
Unlike older versions of software that required a completely separate installation of the entire application, modern AutoCAD uses a core installation. Language packs simply apply a new localized layer over that core. Key Benefits autocad language pack 2023
Solution: Clean temporary files and re-download from Autodesk Account. You must have the base version of AutoCAD