OpenGameArt.org
Forest of Abandoned Souls
Credit line
"Forest of Abandoned Souls" by Alexandr Zhelanov licensed CC-BY 4.0: https://opengameart.org/content/forest-of-abandoned-souls 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.