When you go to create a video via the script editor you're able to have assets and music added automatically from Storykit's stock libraries and music libraries. This feature is extra useful if:
you don't have a project library set up
you're a user who doesn't have asset libraries, or you don't have your assets libraries well organized
This feature is set by default so if you create a new script you already have it toggled on. If you don't want it you need to turn it off.