The ftp 550 error is typically an error from the ftp server, which means OpenVMS and the local file likely isn't particularly relevant.
Check your credentials and your associated access on the remote ftp server. Put another way, this doesn't appear to be an OpenVMS question.
Presuming V6.2 or later, the usual command to push a file from OpenVMS to a remote ftp server would be:
$ COPY/FTP [/binary or /ascii] -
[/active or /passive] -
local-file-spec -
host"rem-user rem-pass"::"rem-file-spec"
(The older ftp utility is still available, but somewhat more involved to script in DCL.)
I'd also suggest switching to sftp, as ftp is problematic in modern networks, and particularly when firewalls are involved. (Though the sftp client isn't yet supported by a hypothetical COPY /SFTP command, unfortunately.) But you can get sftp to work with public key authentication, which means you don't need to embed passwords in your DCL procedures, etc.
If you're issuing a PUT operation from VMS to the target system, or if you're getting a 550 error back from the remote ftp server, then Filezilla and the local protections and related likely aren't relevant.
The Filezilla tool would be a GET from the OpenVMS system into a Microsoft Windows box, and if you're using Filezilla and Microsoft Windows. And that Filezilla tool would also be expected to generate a 550 error given the same set of credentials and a PUT into the same remote ftp server. (Try that Filezilla PUT, for instance, or try an ftp PUT from bash or whatever other client environment you happen to have around on your local network; PUT into the same server with the same credentials, and see if you can eliminate OpenVMS here.)
