The game is using standard hca audio with additional header. You can find "HCA" string and strip everything before it or use attached script to do it automatically (for batch convert). Resulted file is fully compatible with vgmstream. Tested on nsw version of the game.
Alternatively, you can use vgmtoolbox (misc. tools -> extraction tools -> streams -> CRI HCA extractor) to extract hca audio from corresponding sab.bytes files.
You can request AES keys on rin forums
(the list with keys is also there)
AES keys finder and latest UE4 bms scripts: in this post