The language isn't enabled in Windows OS language settings. This is a hidden requirement. Fix: Go to Windows Settings > Time & Language > Language & Region . Add the target language (e.g., French). You don't need to switch your display language, but the OS needs the basic language pack installed for Office proofing to hook into.
The ODT is the official method for downloading and installing Microsoft 365 components without a persistent internet connection.
The ODT is a free tool from Microsoft that allows for customized, offline installations. Microsoft Learn Download the latest version from the Microsoft Download Center to extract the files, which include and sample configuration files. Microsoft Learn Step 2: Create a Configuration XML You need to create a text file (e.g., proofing.xml