Attached is two screen shots. The first shows the System Report with the ThumbDV installed. Notice it is reported to the system as a FT232EX, which is the USB to serial chip used in the ThumbDV to provide access to the AMBE chip. (Click "about this mac', system report and then USB)
The second screen shot is from Buster's preferences, specifically the VoCoder tab. This is what you will see when Buster has successfully accessed the ThumbDV. This should happen automatically unless you have previously told Buster to use the network vocoder option previously. Worst case is just select the Thumb DV option.
If these two things look correct, it sounds like everything is working. Have you tried connecting to a busy reflector (REF001C or REF030C are two good starting points) and seen if you are able to connect/hear anything?