For several weeks Spotify tries to download all songs. Playlists and Albums are set to "download : false", nevertheless all songs in the playlists are downloaded (green). This continues until the SD card is full, then spotify complains about a full disk. Setting albums to "download: true" and back to false does not help. Most of these songs are only included in one album or playlist, not in several playlists where one of them might be set do download: true.
Only when I completely delete the complete album or playlist from my account, the memory is freed (for a short time, then other songs are downloaded as there is now more space on the SD card).