OpenGameArt.org
Synth Shades
Credit line
"Synth Shades" by marcelofg55 licensed CC-BY 4.0: https://opengameart.org/content/synth-shades Author's attribution notice: “Synth Shades”. Music by Marcelo Fernández (http://www.marcelofernandezmusic.com). Licensed under Creative Commons Attribution 4.0 International (https://creativecommons.org/licenses/by/4.0/).
Where to put it: Game credits or video description. If the entry has a "Copyright/Attribution Notice", follow that.