Greetings,
The "Administrator Password" is the password used for logging into ListMail. The "Dailymail Password" is used for the daily scheduled task. There are two passwords for security, as the dailymail password will be shown in areas like web server logs, etc.
Your FTP password has no effect on the operation of ListMail. The only reason you need FTP is for originally uploading the ListMail files.
Please let me know if you have any more questions!
Regards