Most web software doesn't included FTP capabilities, except for potentially reading from a remote server via FTP.
What you want is your server FTP details. This (or using ssh) would be required for any file modifications to the scripts. Control panels in your software are only useful for software configurations, not for code changes (and heaven forbid writing an online editor O.o).
Unless the software's purpose is to provide a web based control panel for the entire site, than chances are you are needing to provide the server level ftp access.
header('HTTP/1.1 420 Enhance Your Calm');