Yes, it needs DP Alt-Mode for the optimal transmission of the image signal via USB-C. But actually, as described above, it should also work with USB3 and the adapter. My experience with three laptops was that it always worked. Even with the office PC where I can't install anything, there was no problem and no special drivers were needed.

It even comes with an adapter for the normal old-fashioned USB ports. But I guess it still has to be USB 3.

Hello,
I can use the display without problems via the USB-C port from the Dell notebook and Dell notebook/tablet. However, it only works via the included USB-C cable (1m long). Other cables with USBC have not worked for me. I suspect that there has been a confection in the cable area here. After all, both signal and power supply are necessary for the display.
I am very satisfied with the display (brightness and resolution).
Best regards
Wolfram