Subfolders - Subsections

Hi,

I'm creating my first rise course. I was able to create a folder and projects within that folder. Within a project I'm able to create sections. 

However I don't seem to find a way to create subfolders or subsections.

My objective:

folder = portfolio of all products; subfolders = range of products

Project = course per individual product containing different sections & subsections depending on topics we would like to highlight about the product (different angles)

Anyone who can help? Is it possible at all? If so, what am I not seeing/doing wrong?

Thanks in advance for the support