You have two ways of adding music to your experience to make it more immersive.
The audio component
In the Pro, Business and Enterprise, you have access to an audio component. You can import your own mp3s or search your track in the Deezer library. To do so, you need to add the component on your screen:
You can decide if you want to enable autoplay and/or sound loop.
Musique in the bot
You can insert mp3 sounds directly in your questions:
You just need to click on "media" in your bot message:
You can integrate a Spotify player directly in your experience.
Follow the steps of this article to add it: https://help.fastory.io/en/articles/3139491-how-can-i-integrate-spotify-to-my-experience
You can also integrate youtube videos to your content by using the same embed component.
You can generate meta images for your mp3 sounds thanks to this website: https://tagmp3.net/