Step 1: Log into your cPanel and navigate to File manager menu
Step 2: Go to wp-content/plugins directory and hit Upload button in order to upload a .zip file from your local machine (or use FTP instead)
Step 3: Once the archive is uploaded, right-click on the archived file > Extract option
Step 4: Once the archive is extracted, you will see the folder of your plugin in the corresponding directory of your WordPress installation
Step 5: The plugin is now installed, you can go ahead and activate it in your Dashboard > Plugins menu.