Instead of using wp_list_categories, perhaps you could add some code to your first attempt and divide your $categories array into two arrays, then output each array in its own column:
From Stackoverflow:
How to split/divide an array into 2 using php
In order to save the total number of posts each time one is created, I think you might need to hook into either acf/save_post or WordPress save_post, where you would update the total count.
Depending on your requirements, it may be easier to just use wp_count_posts when you need to display that number.
Not sure if these will be a complete solution, but here are a few things I noticed:
1. Try adding white space after your opening php tags:
<?php} else {?> // Incorrect
<?php } else { ?> // Correct
<?php}?> // Incorrect
<?php } ?> // Correct
2. Looks like you are missing a closing div for .img-container.
3. Does your code include an endwhile?
You may be able to achieve what you want with some combination of the ‘has_archive’ and ‘rewrite’ arguments when registering your custom post type. Perhaps something like this:
'has_archive' => 'about/employees',
'rewrite' => array(
'slug' => 'about/employees',
)
Don’t forget to flush your permalink settings after making this change, and watch out for URL conflicts if you already have a page at /about/employees/.