Since VestaCP is lagging some features and so the best option for a free cpanel alternative is Webmin.
But Webmin comes with an old school HTML File manager that is not so easy to use. You can install a modern file manager in Webmin using this tutorial.
Pre requisite: Webmin installed and logged in
Step 1: Go to Webmin –> Webmin Configuration –> Webmin Modules
Step 2: Click on the option “From ftp or http URL”
Step 3: Go to Github and copy the file manager URL
Click Here https://github.com/Real-Gecko/filemin
And open the distrib folder. There will be two files, as shown below
Open the Filemin-x.x.x.freebsd.wbm.gz
REMEMBER! Open only freebsd file only and not the another one.
Step 4: Copy the URL for the view raw and paste it on webmin
Step 5: Click on the install Module
DONE!!! Enjoy a better file manager with Webmin.