Help With Illustratr Theme Drop Down Menu

Hello. I am using the WordPress theme Illustratr.

I can not, for the life of me, figure out how to create submenus that drop down. I am using it as the project style and I am using it for my portfolio.

I have set up my project types, but when I go into the menu customize, they don’t show up, so I can’t use them as submenus.

Am I just totally missing something here? I just want my categories that I have each individual post under (which does show up under each individual project), to show up in a drop down menu.

Can anyone help? Thank you so much!