Dell Optiplex all-in-one On-screen display application

I have a dell Optiplex all-in-one 7470. I want to use the all-in-one as an extra monitor for my laptop, so I installed the correct software from https://www.dell.com/support/home/en-us/drivers/driversdetails?driverid=prgt0 . Rebooted the computer, connected external input to the hdmi input on the all-in-one, but nothing happens. What am I missing?