Thanks for reporting the problem. This may be related to what has been addressed in Spotify does not play audio
I understand that you do not use wayland. Do you use pulseaudio? Can you do:
$ ls -l /run/user/$(id -u)/pulse
total 4
srw-rw-rw- 1 maciek maciek 0 02-05 07:04 native
-rw------- 1 maciek maciek 6 02-05 07:04 pid
There should be a socket there. Another way for pulseaudio to find the socket is to look at properties of X root window, can you try:
$ xprop -root | grep PULSE
PULSE_SERVER(STRING) = "{9152da7600c94619af668cc8f273730c}unix:/run/user/1000/pulse/native"
PULSE_SESSION_ID(STRING) = "c2"
PULSE_ID(STRING) = "1000@9152da7600c94619af668cc8f273730c/19383"
Lastly, can you try to run spotify like this and post the log?
PULSE_LOG=4 SNAPD_DEBUG=1 SNAP_CONFINE_DEBUG=1 /snap/bin/spotify