Insert Comment Box shortcode

Hello, I have a Private content area on my website the software is called “Customer Area” and I use this to create my client’s custom workout routines/pages. (www.MattJamesFitness.com)

In the Clients Only area I would like to add a “Comment Box” at the bottom of the page where we communicate for each client but the “Customer Area” doesn’t use the avia framework just the default editor. How can I go about adding the comment box to these pages? I can add one to all of my normal enfold pages no problem. I tried to find the shortcode to try and copy/paste but I can’t find that anywhere as well. Thanks.