Where can I get a Dutch language pack for spelling correction for the Windows version of Publisher?
Anything built for Hunspell should work, which means anything built for OpenOffice or LibreOffice, too. The LibreOffice collection on GitHub is often a good starting point, and you can find their Dutch set here: https://github.com/LibreOffice/dictionaries/tree/master/nl_NL
You need the .aff file and the two .dic files.
Edit: Downloading the files is tricky. If you're not careful you end up downloading an HTML page instead, which won't work. This approach should work:
Click on the