I’m not referring to the music from the official games, obviously. Those are easy enough to find. I’ve been trying to find relatively updated forums/blogs where download links for this music is shared. I’ll start dumping some of these blogs I find, and if you know any of them, feel free to share!
https://www.tapatalk.com/groups/bunbunmaru/musica-de-touhou-f13/index-s100.html (this type of forum is so nostalgic holy shit)
If it’s weeb maybe nyaa.si? Apart from that I have no idea.
I just tried searching some albums on that site, sadly it’s mostly concert rips and fan recordings. I guess you have to try searching with specific bands/circles.