Assets sub folders can be achieved by adding tags to assets. This creates a sub folder that can be viewed by clicking on the folder icon from the Assets library or a Playlist.
1) Click on the ‘Manage Tags‘ icon:
2) Click on the ‘Add Sub Tag‘ button and create the new tag:
3) Assets can be moved to sub folders by dragging the asset into the folder, or click on the asset from the library to open the Media Detail for that asset. Click on the ‘Tab‘ to add a tag to the asset: