Sigh.

I used this: https://www.zen-cart.com/downloads.php?do=file&id=159

And I didn't touch the install SQL file.

I didn't incorporate any code changes posted in this thread, as I haven't studied the 700 previous posts here.
I did observe that there are probably a number of things in the admin pages of this plugin that could probably use improving. I did touch those just to fix some potential sanitization issues and HTML markup errors, and PHP compatibility issues.