Music tracks are categorized by genre (e.g. ambient, cinematic, classical, pop, reggae) and mood (dark, funky, sad, etc.). You can listen to them online and download them as MP3 files.
Here is “Bubble Walk” by Aaron Lieberman (categorized as ambient and funky):
There is also a large collection of sound effects. These include Creaking Wooden Door, Dissecting a Body, Human Eating Watermelon, Subway NYC In Motion, Thunderstorm, Laundromat Sounds and so on.
This is a Monster Alien Grunt Hiss: