I want to use the unit with a DJ application other than Serato DJ Pro by assigning MIDI. Where can I find the related information?

The MIDI message list is available [here].

When Serato DJ Pro is running, the unit can be used as a controller suitable for the Serato DJ Pro features.
However, you can change the setting to use the unit as a general MIDI controller regardless of whether Serato DJ Pro is running.

For details, refer to the Instruction Manual > [Settings] > [Utility settings].
You can read the Instruction Manual [here].