When trying to upload certain folders to a websites public folder as the default FTP user that is created when you make a site in STORM, you will get a '550 etc: permission denied' error. This particularly impacts folders called etc or lib as they are also the names of root system folders on a Linux OS.
For security reasons, it is not possible to create/modify sensitive directories via ProFTPd, this is to protect and against the BEAST exploit. By default, attempts to do any kind of write to a path under
'lib' in the root folder will be rejected. Please note that this is default ProFTPd configuration, not STORM.
To work around this you can add an additional FTP user and set the path as / instead of /public. Another way is to use the SSH details contained in the website to connect over SFTP.