As stated by IMDb:
The music department list includes all music jobs not already covered by the composer or soundtrack lists, and should include the following:
Musicians
Orchestrators
Music contractors
Arrangers
Additional Composers
All credits related to recording and mixing music.
Any music-related credits except composer (songs by, lyricist, singer, musician, arranger, song or music producer, etc.) that do not appear with a specific song or music title.
The question here is are you the “composer” or “additional composer”…