You are trying to enter the FTP site using HTTP protocol.
the full URL should be "ftp://ftp3.fabriclabs.com/"
The site appears to require entry of user/password information, which should also have been provided to you by your client.
You may also want to consider using a dedicated FTP client application, such as CyberDuck, Fetch, Transmit, Captain FTP and many others. A search at VersionTracker or MacUpdate will serve up a long list of shareware, freeware and commercial solutions.