Why can't I put a Dropdown into any element I want (Particularly, span)?

I'm finding the heavy handed restrictions of BSStudio rather frustrating.

I have a requirement for a nav bar, and in that nav bar I want to have two sections. One for the main set of menus that I will centre and another that's on the right for a few others like Cart and Account. I want Account to have a drop down menu which I can do if I add another Nav element. However, I want cart to be a Button but it won't let me drop a button onto the Nav. Then I tried having one Nav and a custom Span. I can now put a button in it but I cannot put a Dropdown.

Can I unlock this stuff so I can do whatever I want?

The aim of BS Studio, I thought, was to speed up development but now I have done 90% of our company's website, I feel I have spent MUCH more time wrestling with the software that I could have likely just used React or handcoded bootstrap for most things and taken a similar amount of time.