The Category Image Plugin allow you to add image with category.

Noted That:

To install correctly this category-image.zip.
Fisrt Download the category-image.zip to your computer
Extract/Open category-image.zip to Your Computer.
Then, Find readme.txt file inside category-image.zip and Open readme.txt.
Now, Read the Requirements of this plugin. Which Wordpress Version and PHP Version are required to run this Plugin in Your Wordpress Site.
Then, Follow the the Tips Below.

Start the Tips:

1. First Download "category-image.zip" Plugin to your Local Computer. (Click Download)

2. Then, Login to your "yourdomain.com/wp-admin" Dashboard.

3. Then, Click on "Plugins" + "Add New" from left sidemenu of Dashboard.

4. Now, Click on "Upload Plugin" button.

5. Now, Browse "category-image.zip" Downloaded plugin from your computer, Where you downloaded category-image.zip According to Step – 1 Above then, click on "Install Now"

6. Now, Click on "Active Plugin"

7. Then, See left sidemenu. "Category Image" folder is added on left sidemenu. Now, Click on "Category Image" folder.

Noted that: If you do not see "Category Image" folder on left sidemenu then, see at left sidemenu "Settings" or "Tools".

8. Now you configure yourself oR Watch video tutorial below about Category Image Configurtions and Settings or How to work "Category Image" in your WordPress site.

After Activated Plugin According to Step-6 then,

Go to "Plugins" + "Installed Plugin" from Wordpress Admin Panel Leftside Menu.
or Direct go to: https://yourdomain/wp-admin/plugins.php
Then, Find "Category Image" Activated Plugin from Plugin List.
Then, Click on "Settings" from Plugin that is Category Image
Now, Edit/Add/Config the setting and Click on "Save Changes" button,

Guide

Guide
You can install Category Image directly from the WordPress admin panel. `Visit the Plugins > Add New and search for 'Category Image'. Click to install. Once installed, activate and it is functional.` Manual Installation Category Image plugin: `Download and unzip the file Upload the full extracted folder to the /wp-content/plugins/ directory * Maintain the directory structure of the archive (all extracted files should exist in 'wp-content/plugins/category-image/' Activate the plugin through the 'Plugins' menu in WordPress.` You’re done! The Plugin ready to use according to the directions in the description. More documentation Go to http://pankajanupam.in/wordpress-plugin/category-image

You can install Category Image directly from the WordPress admin panel.

Visit the Plugins > Add New and search for 'Category Image'.
Click to install.
Once installed, activate and it is functional.

Manual Installation Category Image plugin:

Download and unzip the file
Upload the full extracted folder to the /wp-content/plugins/ directory
* Maintain the directory structure of the archive (all extracted files should exist in 'wp-content/plugins/category-image/'
Activate the plugin through the 'Plugins' menu in WordPress.

You’re done! The Plugin ready to use according to the directions in the description.