Inside ／assets／6dba there is data1.dat, which seems compressed/encrypted. There is no audio in the assets (except one minuscule FSB5 sfx which is not worth it). Maybe the music/audio is downloaded in runtime; you should explore your data folder in your android device.
The music and audio is in AB (Android Backup, or Asset Bundle) files when they are extracted or downloaded. Is there any way to extract them with a tool or a program?
You need to have root access on your device if you want to find & copy them, as they might (i.i.r.c.) be located in a hidden, restricted-access folder (typically "/data/data/<apk_name>" for INTERNAL, "Android/data/<apk_name>" for EXTERNAL/SD).
<pk>\assets\bin\Data\* seem graphic files. All files from the OOB look encrypted. For the files extracted from the AB "containers", their first 0x20 bytes are the same, and seem to be some kind of header (maybe used for decryption?). I found "zencryptoutput" strings in ALL of the files in assetbundle. Maybe that's their origin folder? (pre-packing?) The files are extracted from the assetbundle. It's incomplete, but at least it shows that every file is encrypted.