Can't edit Navbar menu (Custom Navbar)

Hi guys, I am using a template provided by siv.
Apparently they don’t use the standard navbar. My issue is that i can’t edit the hamburger menu (the secondary screen that opens once you press the hamburger menu).
Usually one can open the menu through the navbar, right?

My navbar is a div though, so there is no option of “open menu” anywhere.

I am losing my mind, please help me haha.

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