Custom Term Colors

SOS

Do I have to place some code in my theme?

No or maybe yes. You can use the plugin as it is, just to differentiate terms by color. However, if you want to display
the colors on the front-end, you may need to use the CSS class, that is something like .ztc-term-label-{ID},
or directly get_term_meta to retrieve the meta value.

I want to display the terms on front end how to do it?

The easiest way is to use the built-in function that comes with this plugin:
ztc_colored_labels( $taxonomy, $post_id = false, $links = false, $limit = false );