If you get a blinking red LED that means you pushed the setup button by mistake. Just push the reset button and it will be ok. If the red led stays on there was an error. Press reset.
If nothing happens in the ArtBus_term window, or if you get a bunch of error messages in Processing's terminal window, then the FTDI driver isn't talking properly to Processing. This could be because
When you start ArtBus_term.pde with everything connected, a list of serial ports appears at the bottom of the Processing editor. On Mac they should include one that looks like "/dev/tty.usbserial-FTQVBIO0". On Linux it should look like "/dev/ttyUSB0", on Windows like "COM9". Processing wants to know which one on the list to use in the sketch and for that number to be put in the [ ] in the line below:
port = new Serial(this, Serial.list()[0], 115200); //Choose serial port from list
Serial.list()[0] means the first serial port in the list, and [0] works almost all the time on Mac and Linux. Other values could be [1] or [2], etc., which is useful to know for Windows.