Thank you very much,
From what I can see on the manufacturer web page about the product restrictions, this isn't a product using DisplayLink technology. Otherwise it wouldn't be only supporting one display on macOS (the asterisk) in specific plug combination.
https://www.iogear.com/product/GUD3C02/
You can also look at the product datasheet, this is an Alternative Mode Product, not a universal USB one.
The DisplayLink driver is no use to you as you don't have a product with our techno in it.
I recommend you contact the manufacturer for assistance on their product.
Kind regards,
Alban