Just want to share this great and easy tutorial with Pydio File Manager. No code modification needed. https://www.sukalupa.com/blogs/ispconfig-3-file-manager-with-latest-pydio-8-2-0/
just so everyone's aware. I've tried this previously, with ispconfig 3.1.13 (multi-server) and I had problems. the software itself worked, and looked good. but there were security issues. basically, I could login with different ftp users and if I changed a file, I would then see the changed file when I logged in as a different user. if I requested a file list, it would list the files that matched those that existed in the logged in users folder, but with timestamps that matched the user I'd just logged out as. not sure if it was really seeing/accessing the files from a different users folder, or if it was just a caching issue. or even if it's just an issue that only affected ispconfig multi-server and that a standalone server would be ok. I didn't have the time to look into it any further, and since pydio have completely changed their software and how it works, I didn't expect this older system to keep support for much longer. although I see now they've updated it to v8.2.3 back in march. so if anyone does try it, I would recommend using a test system first and check it thoroughly before putting it on a production server.
I tried pydio before but I didn't manage to get it to work properly with ISPConfig servers. The only working webftp with ISPConfig servers I tried are net2ftp and elfinder. Net2ftp is kinda good but for the time being I am using ElFinder.