This is correct, please verify that you are pointing to the fully extracted directory containing all the SWBD floders. I commonly see people extract the folder to an additional nested folder where the path is actually /nos4.1.3d/nos4.1.3d/
Did the copy command with the running configuration work? Maybe you need to specify the mgmt-vrf.
This would not apply to NOS 4.1.3d as VRFs did not exist until the release of NOS 5.0
I would also like to know if you were able to copy the running config to the FTP server. This would confirm that at least the UN/PW and connectivity are not an issue. If this is the case, the issue has to be with the file path.
You can also try logging in to the VDX as root and then using normal ftp commands to connect to the FTP server to confirm UN/PW and file path.
Hope this helps,
Principal Technical Support Engineer