I hope you have loaded the sample data for theme. Otherwise, I strongly recommend you do so at least on a dev site to speed up development. Here is the video for loading the sample data in case you need it –
https://www.livemeshthemes.com/support/faqs/how-to-setup-theme-and-revolution-slider-in-10-min/
The client list itself is a simple shortcode+ HTML. Have attached an example of the same.