Currently, 19 releases from The Adaptive, In The Branches, and Infinite Brothers (singles, EP’s, and albums) are FREE to download on Bandcamp until further notice. That’s a lot of ambient and electronic music. You can pay more if you want to support these projects, but the minimum price for nearly every release is zero.
Bandcamp gives several options for audio format when you download. I recommend choosing 320kbps MP3 format for CD-quality sound, but choose WAV or FLAC if you want the original (24-bit) masters.