setup.exe /configure proofing_config.xml

By default, when you try to use a language not installed on your Office 365 suite, Microsoft 365 apps will prompt you to download the proofing tools from Microsoft servers. This "click-to-run" method requires:

Select from the dropdown menu and choose your language.

: Run setup.exe /download configuration.xml on a machine with internet to pull the offline files.

You can copy this folder, but this is a reliable installer — it may miss registry entries.

To achieve a purely offline deployment, administrators or advanced users must pre-download the files utilizing the command-line Office Deployment Tool (ODT).