It seems as if the website hasn't updated the links yet, although the manuals have been updated - therefore the links are broken.
You can copy the links and change the URL to the appropriate version (in your link, V3.22d not V3.22c) or alternatively wait until the site updates the links. Sorry about that.
Older versions of the Matrix manuals can be downloaded from the Documentation Download page. You’ll need to go through the pages to find the manual you are looking for. The manuals are listed newest first, so the 3.22 manuals will be towards the back.