Hi! I was hesitant to reach out to the manufacturer because of a ... branding? purchasing? issue - I ordered a Monoprice from Amazon and got a Lapazz, and to this day I'm still not sure which wires were crossed or why that happened or if I got duped into buying a knock-off or something. But at your advice I did reluctantly do some digging and did find a tablet that looked just like mine (except with a Monoprice logo instead of a Lapazz one, maybe they just renamed the company or something, I have no idea) and went ahead and downloaded the installation disc for it, which the website provided. (Link, just in case anyone's curious: https://www.monoprice.com/product?p_id=6814)
I can now see the tablet in the device manager, and the cursor moves! Unfortunately, if I have both monitors active, it tries to map itself to both (which means it is oversensitive to horizontal motion but no so vertically), and the calibration screen still does not work - at the "Tap this screen with your tablet pen to set it as the Tablet PC screen" stage, when I tap, nothing happens - but if I set my display to only work on the external monitor, it will ... well, more or less go where it is supposed to. Still feels off by a few pixels, so I think possibly there are a better set of drivers out there somewhere, but it's functioning enough that I think I can get by with it!
I will try the troubleshooter if I run into anymore problems - right now I suspect this setup is being held together with metaphorical duct tape and crossed fingers. Thanks so much for your help!