When an addon has audio: true in their config, more detail should be in selecting which output when you have multiple, than just “Build-in Audio Stereo”.
My Pi 4 technically has 3 audio outputs, the jack, and 2 HDMI ports. I’ve nothing in the jack, and a cable in HDMI slot 1.
I’ve just installed and set up the Spotify Connect addon, and because there was no sound initially, I checked the configuration and was greeted by
From previous OS installations, I assume one of those is jack, and the other is HDMI output. When I selected the second option, and restarted the addon, audio worked perfectly, so it seems everything’s good, apart from those generic labels.