I have encountered the same problem: ‘Table dbname.wp_categories doesn’t exist.’ I checked my database, and that Table indeed does not exist. My categories are working okay, so that’s not the problem. I think there are two possibilities:
1. The table is not being created by the install part of the php script due to a bug in the script.
2. The table existed in earlier versions of WordPress, but not inthe one I am using (2.92).
I Have not investigated either of them, but I may do so later, but first I’m going to try to check to the author of the script.
Not much help, I guess, but at least it is some more info.