Question about Hannspree HT225HPB

Hello,
You need to connect the USB and HDMI cables to the PC. The touch screen will then be seen by Windows (Win 7 and above) and requires no additional driver. In generic terms, the touch screen will be seen as a mouse, pressing down on the screen as a click, and pressing down on the screen for 2 seconds as a right click. When the application supports touch mode, it will be seen as a multi-touch surface. However, macOS does not support the touch screen natively. This screen's touch mode cannot be used with Android or iOS.
It should also be noted that the touch mode is capacitive, as with a laptop or table, so it doesn't work - or works poorly - with gloves or wet fingers.

Have you connected both cables? (HDMI and USB)