Hello,
autoUpdate enables an internal option in the DOCX to ask the program used to open the DOCX to update the TOC (asking the user when the DOCX is opened). This options is only compatible with MS Word.
To update TOCs in DOCX documents, you need to use the conversion plugin based on LibreOffice or MS Word. To use the LibreOffice one, please check the docs folder included in the package, you need to add an use a macro.
Regards.