If the pack isn't downloading, check your regional game license. If it keeps failing, uninstall the game, switch your console region to the target language's country (e.g., France for French), and reinstall the game fresh. The language pack is tied to the initial install data.
A language pack for Wolfenstein II: The New Colossus adds localization — translated text and/or voiceovers — so menus, subtitles, and sometimes spoken dialogue appear in another language. Some packs include only subtitles and UI text; full voiceover packs replace spoken dialogue as well. wolfenstein ii the new colossus language packp