They are claiming that those URLs violate their copyright interest in some obscure music album. This is obviously an erroneous DMCA claim, filed either maliciously or by mistake.
These kind of things are often due to overly broad or malfunctioning algorithms. Maybe some algorithm just picked up a list of links ending in "download"?
Even if that's a mistake, it looks like gross negligence. These URLs aren't even tangentially related to music.
