I have 2,109 Categories. I am nothing but thorough when tagging photos. I wish to know about getting those categories into keywords and then into the 240,000 photos.
Have you used the search engine in the community to find what you are looking for?
You can use Google, e.g. searching for "IMatch categories into Keywords".
Or just look into the IMatch help: Copying IMatch Categories into Keywords (https://www.photools.com/help/imatch/#md_templates.htm?dl=h-14)