One audio clip for entire Story project

Hi Andrea, 

Thanks for reaching out! 

You can check out this community thread on how to add background music to a course which has received a lot of positive feedback from the community. 

• Background Audio Cool Trick

I also added this thread to a feature request that we have for the additional of a built-in feature that support continuous audio tracks in Storyline 360. We'll let you know when this feature makes it to our roadmap!