You can add a testimonial list in any page or post you want. There are two ways to add it to your pages;
Inserting a Testimonials Element (via Visual Composer)
Click on the add element (the + sign) in the visual composer and add a Team module / element.
Inserting Testimonials by a shortcode.
Click on the shortcode button in the admin bar in the popup window select the Testimonials Shortcode, adjust the code to your need and copy and paste the shortcode into your page content at the location where you want this showcase to appear.