Click your windows key and type "sound mixer options"
Now find your spotify application and select the first box and set it as your preferred track
Now play a song on spotify and you should see it picking up the input
if you can not hear it, make sure you have the correct "A" Channel set to match your Output
Now if you wanna play anything in-game, select the B-1 or in some cases the B-2 Channel on voicemeeter.
I have everything running through Voicemeeter so id just add your Quest 2 microphone and speakers onto voicemeeter and mute the mic from there.