If nothing happens in the ArtBus_term window, or if you get red 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. Other values could be [1] or [2], etc.