I think that the first reply to your post was on target. I have looked at the Net::FTP doc's and this appears to be "spot on". I suspect that your problem is at a much higher level than just getting the file. First, you have to authenticate and get logged-on. Follow the steps below.

use Net::FTP;

$ftp = Net::FTP->new("some.host.name", Debug => 1)
  or die "Cannot connect to some.host.name: $@";
   
$ftp->login("your_name",'password')
  or die "Cannot login ", $ftp->message;

$ftp->cwd("remote_dir") #cwd at remote site may not
                        #be necessary depending upon your logon.
  or die "Cannot change working directory ", $ftp->message;

$ftp->get("somefilename")
  or die "get failed ", $ftp->message;
[download]

Wish you well...