The developer system is a single-user system --localhost, plus 1 external IP address (for testing).
The developer version is not suitable for use on a network, and to do so would be a violation of the license agreement,
That makes this question academic for the developer system.
In a licensed multi-user system (30-day Trial, development or production) authentication is provided by a combination of the underlying OS's file permissions and htaccess (or similar service) provided by the web server.
Since the OS X port of CFMX cannot be interfaced to any web server except the CFMX-supplied default web server, web server authentication is not applicable to the OS X 30-day Trial system.
I can't speak for Macromedia, but, for the reasons above, it is unnecessary to provide any authentication for the developer system.