That isn’t an FTP server. That’s ssh. So, use the ssh option.
If you want FTP, connect to an FTP server (which is not port 22 and is not using FTP over SSH protocol). There’s FTP over TLS which is FTP, but there is literally never a reason to use FTP in a world with ssh/scp.
Filezilla is not just an FTP client. It also support ssh. But, an FTP client (that only supports FTP) cannot talk to an ssh server, and the FTP client Virtualmin uses is not also an ssh client.
That’s also ssh. ProFTPd is also an ssh server (well, just FTP over ssh, it doesn’t allow a login shell), and we configure it on port 2222 for convenience for people who want FTP over SSH and limited access for users (safer/simpler than chroot, and no shell possible).
FTP is port 20 or 21, plus optional high ports for active FTP. But, just use ssh.
Just use the right protocol in Virtualmin’s destination configuration for the server you’re talking to.