If you own the Ultimate Chicken Horse original soundtrack electronically or physically, you have permission to play it in the background of your streams without the need for a license or written agreement.
This is thanks to the kind folks at Vibe Avenue, who chose not to distribute the soundtrack through a publisher that would collect royalties from reproduction rights. It means that you never have to worry about DMCA claims on your content if you play Ultimate Chicken Horse or its soundtrack on stream.