Multiscreen not working HP USB C Dock G4

Hi all,

I have a HP USB C Dock G4 on my Macbook Pro 15'' 2017 with Touchbar and i would like to use a multiscreen setup. Now i have the screen of my Macbook and 2 external screens, 1 on the HDMI port and 1 on the Displayport. The external screens are duplicating the same output and the Macbook is the main screen..

How can i use this dock with 3 screens without duplicating a screen..?