ESP32 socket FTP server can be found her: GitHub - BojanJurca/Multitasking-Esp32-HTTP-FTP-Telnet-servers-for-Arduino: ESP32 with HTTP server, Telnet server, file system, FTP server FTP client, SMTP client, cron daemon and user management
Supports active and passive mode.
You can configure it to work without username/pasword.
If you need only FTP server just exclude (delete) Telnet and HTTP servers and everything that you don't need.