Make sure you are using DP4.12 and have downloaded and installed the MAS/AU update available in our Downloads section.
• Launch the "FW-1884 Manager." (found in the Applications folder)
• Under the Settings panel, select the control protocol to "FW-1884 Native" and
in the Core Audio panel, select how you'd like to use your FW-1884
(as an 18, 8, or 2 channel device).
• In DP4, goto the Setup menu and go to the Configure Audio System >Configure Hardware Driver.
Select FW-1884 as your hardware driver.
• Next, goto the Setup menu and go to Control Surface Setup.
Select FW-1884 as the driver as well as the MIDI port.
This will get your FW-1884 working with DP4