Addons are not able to play custom sounds, only the available ingame sounds of the table _G["SOUNDS"].
And if you like to extract the audio, you need to extract it from the files of the client using EsoExtractData (if it also extracts audio, only know of the .dds texture files and source codes. But current PTS file structure changed so EsoExtractData needs to adopt for Harrowstorm client files!).
See here, or on UESP website:
https://www.esoui.com/downloads/info...tractData.html
Manual:
https://www.uesp.net/wiki/Online:EsoExtractData