Just verifying you are using basic FTP or FTPS, which the ReadyNAS supports, not SFTP, which it does not. And if using FTPS, that the appropriate checkbox is selected on the NAS under FTP.
Have you tried using SMB, just as a test if nothing else?
FTPS is a checkbox available when you enable FTP. While SMB is a Windows protocol, it is supported by the ReadyNAS and your screen print shows it is enabled. AFAIK, it is also a selectable as the connection type in ExpanDRive. Of course, current Mac OS's also support SMB, so I'm not entirely sure why you are using ExpanDRive.
SMB certainly works with MacOS. FTP is enabled (at least on the backup share).
FTPS is enabled as optional by default - so that's not the problem. Also, FileZilla is giving a bad password error - if @prof290546 were trying to use SFTP, you'd get a different result.
If you want to pursue using FTP, then I suggest either changing the admin password on the NAS, or creating a new account (with a different password) and try that. Chose a password without special characters as a test.
One thought: Is the admin password on your NAS still the default? There are some things that are intentionoally disabled for the admin user when it is, and maybe FTP is one of them.
