Greetings!
The example link you sent, appears to simply be a website application that then connects to FTP on a service and provides a graphical file management experience. There are several such applications available out there that you could install. Here's a few external resources I found:
Web based File Manager in PHP, Manage your files efficiently and easily with Tiny File Manager
tinyfilemanager.github.io
PHP Script with advanced features like multi-file upload with progress bar, zip, unzip, drag'n'drop, amazon s3 support
filegator.io
The Best 7 Web-Based Free File Manager written in PHP Free and powerful File Managers Based on PHP, ready to use in your web projects,
www.dreamcss.com
Alternatively, might I suggest bookmarking this URL:
https://$ipaddress:2083/frontend/paper_lantern/filemanager/index.html
Then you can log directly into cPanel's File Manager tool, as the domain account user. Admittedly the URL is decidedly less wieldy, though you could make a redirect page to it from the domain, if you wanted.
I hope this helps. Have a great day!