OpenGameArt.org
Land of the Great Gods
Credit line
"Land of the Great Gods" by Alexandr Zhelanov licensed CC-BY 4.0: https://opengameart.org/content/land-of-the-great-gods Author's attribution notice: https://www.youtube.com/c/AlexandrZhelanovsMusic
Where to put it: Game credits or video description. If the entry has a "Copyright/Attribution Notice", follow that.