Hello @dq828. Not dumb questions! If they have Spotify, they can use the Spotify Connect plugin on Volumio. the native app is currently not working, but the Connect one works well.
To stream music from phone or computer is possible using Volumio’s bluetooth, but I can’t really recommend it for stability or quality. I have my music files on an SSD drive connected to one of the USB ports of my Raspberry Pi, which runs Volumio, with a DAC hat on top. This gives fantastic sound quality and you can use your phone or laptop to search and play the music. So the hardware is a Pi 3 or 4, a DAC hat like the Hifiberry DAC Pro and a USB hard drive or SSD.