Dropdown with arrow key navigation

Hello. I would like to make a dropdown item with arrow navigation. By this I mean, when I type, the dropdown list shows, if I press down arrow, the first element in dropdown gets highlighted when I press down arrow again, the next item gets highlighted etc. The same applies to vice versa. When I press enter on the highlighted element, the value of that element must apply to dropdown and dropdown list closes. How can I make this arrow navigation? Can not make it work. I try with focus but I need focus to navigate with tab through other elements.
Below is the RP of how far I have come

dropdown.rp (50.8 KB)