I think I may have fried my card, but I'm not sure.
As I always do, I plugged everything without reading the manual (because I think I'm sooooo clever), and plugged the 4 pins of the USB adapter, INCLUDING the +5V, which, I learned later, must NOT be plugged.
I first started playing with hardware in Basic, reading the control port and receiving only 255, meaning that a byte was available (and the byte is always 255).
Then I read the manual, disconnected the +5V, but the result was the same.
The reset and pause buttons work fine, so I guess the hardware is not so fried??
Also, Windows 10 recognize the COM port, but names it "PL2303HXA PHASED OUT SINCE 2012, PLEASE CONTACT YOUR SUPPLIER."!
The COM port is in the dropdown box of the Windows software provided with the USIfAC, but when clicking on "connect", a pop-up shown with the message "Serial interface exception".
Am I doomed to order a new hardware?