Select "USB" (or "Virtual USB Port"). Do not select "Serial" unless you are using an RS-232 cable.
Connect the USB cable only after the software prompts you. Plugging it in early often forces a generic "USB Printing Support" driver that fails later. Driver Printer Panda Prj-80us
When the dialog box says "Please connect the device," plug in the Panda PRJ-80US and turn it on. Windows will chime (device connected sound). Select "USB" (or "Virtual USB Port")
Right-click the driver executable and select Run as administrator . This allows the installer to write to protected system folders. Driver Printer Panda Prj-80us