Tell us about yourself!
I'm not sure. Without seeing the patterns folder and showing that you added a new source i can't determine what went wrong. But this article covers patterns in. Much greater detail. It should help you identify a solution https://docs.gimp.org/en/gimp-concepts-patterns.html
As a content creator I don't make the PDFs but the majority of the instruction is in the video so a PDFs version would just contain the list above