Most Cypress chips are able to enumerate without any
code as the default Cypress device.
For this device Cypress provides anything neccessary
(Drivers + INF)

Unknown device means that WIN did not load any drivers
for this device which is the case when you cancel the
driver dialog.

Try to update the driver and point to the right folders
for the inf and sys
If this does not work there is something worng with
your HW or you are using the chip with a brocken FW

BTW:
there is no such thing as default usb device.
Usb devices belongs to classes like HID Audio...
or you have to provide drivers for the device like
the Cypress Sample driver.

Thomas