Dumb question, where do you actually buy digital copy of music these days? Or find a big library of music that you can download.
Bandcamp, and when what I want isn’t there, qobuz usually has it. A couple of times I’ve had to buy the CD off eBay and rip it.
I buy CDs and rip them myself. That's technically buying a digital copy of the music, since CDs are digital.
i use bandcamp whenever possible
Qobuz and 7digital both have extensive libraries of high quality music.
Edit: and of course bandcamp exists but I wouldn't call their collection extensive.