The USB Versions of the old blueMobile and plusPads which are not produced anymore (since 2009), has an intern USB/COM Chip which requires a driver. The new Windows Versions have a Prolific Driver, but unfortunately this driver version is not compatible with the old signature pads. You need to use the old Driver from 2009 which you can download here:
After the installation of the Setup you need to open the Device manager, search for COM and & LPT Devices.
You need to select "Update driver" of the "Prolific USB-to-Serial Comm Port device"
Next you need to click on "Browse my computer for driver software"
Next select the Option "Let me pick a list of available driver on my computer"
You should see at least 2 different driver Versions, you need to select the Version 126.96.36.199 from (17.07.2009)
The installation of the device should be successful and the warning icon inside the device manager should be resolved.