On the Startech.com site it is quite unclear how the product works.
But the original manufacturer of the Trigger VI T6-688SL chipset states it quite clearly; a driver is needed, so it is an external graphics card. The restriction to 1920x1080@60Hz also makes sense, since 4 monitors have to be supplied via a USB 3.0 line. The current driver is also offered here.
https://www.mct.com.tw/product_d....