Original and public domain works are sometimes not free to download regardless of license

An example is this https://musescore.com/user/327166/scores/1550836, which is licensed as CC-BY-NC-SA or CC-BY-NC in other places, but downloading needs a PRO subscription. The specific song is licensed as "all rights reserved" both here and on Newgrounds, most likely because the author forgot to update the LachlanInc-era original works other than announcing a name change.