It seems strange to me that you no longer have a free HDMI slot on your docking station. However, the screen has VGA. You might find a solution under this youtube link https://www.youtube.com/watch. However, you need a free USB 3.0 port on your docking station.

Can this also be done via USB? Unfortunately, my HDMI and RGB slots are already occupied.

Hello
I have connected a Dell screen to my ACER laptop via HDMI cable. Runs tiptop.

Initially I had a Digitus HDMI A to VGA converter connector. This did not work properly. There were always screen interruptions.