Surely you can customize it but I am not in for it yet. You can try discussing your issue in https://github.com/Studio-42/elFinder/discussions or get the developer to help you with it.
Submitting a new merge request to fix minor error of php-fpm version not passing correctly @till I will rewrite this in php and propose another merge request to add this to ISPConfig autoinstaller with option --use-elfinder but will also maintain this in tool section for those who need it after ISPConfig install.
