[Plugin: Post Category Index Generator] Post and Categories index generator not showing anything

No, you don’t need to add any css or other code. The only thing that the plugin needs is the shortcode on a post/page like the examples on the plugin install page.

As for your problem you need to provide a little more information like what shortcode are you using. The first thing I advise you is to check if you insert the category slug correctly since it is one the things that might cause no category or page appearing.

I’ve never used shortcode, only slugs, and I trust those are all correct…it might be wise for me to run over my post list to be certain, though…

From what I read from your answer, you probably are confusing the terms, when I’m mentioning shortcodes I referring wordpress shortcodes which is text that you place on a post/page and wordpress replace that text with something else. (more info here https://codex.www.ads-software.com/Shortcode_API).

As for my plugin, in case you didn’t noticed, the shortcodes for my plugin are here: https://www.ads-software.com/extend/plugins/post-category-index-generator/installation/

You post here the shortcode that you are using I can check if it is correct or not and give some advice.

I see now what is meant by shortcode. Being a very non-technical person, I’ve never used shortcode in my life, LOL, I just use my blog mostly for a “scrapbook,” a means to display a growing collection of photos, not much else.

Perhaps this is the reason the plugin isn’t functioning for me? =/

Well, I believe even if a person that considers itself a non-technical person can learn things out of their area of expertize if he/she dedicates some of his/her time.

As for my plugin I suggest that you try the first shortcode exmple on the link that I provided, which is the simplest, read what each parameter does and work from there until you achieve what you want. If you have any doubt you can post here and will write back.