Can this unit be used for MIDI control of DJ software?

Yes.
This unit can output MIDI messages linked to button and control operations from the USB terminal so software on a computer or mobile device connected to the USB terminal can be controlled by operating this unit.
For details on the MIDI messages output from this unit, refer to the MIDI message list on the support page.
For the audio and MIDI setting procedures of your DJ software, refer to the operating instructions of your DJ software.