I am in a similar situation, so I tracked through the various messages and ended up with Marco's procedure in the files section for connecting my Exos 2 to ASIAIR Pro. Its very good even for the layman like me!
I already had a serial to usb cable as I have been running with a wired connection so, came to re programming the chip, downloaded the programme and scanned for devices and nothing.
Is it likely that having bought the cable from Amazon that it does not have a chipset but just looks like one? ( I paid about $12 UK £10)
I have been on a specialist site which sells them for about $30 and they are manufactured by FTDI.
Any advice would be greatly appreciated
Telescope AR102, F6.5
Exos 2, PMC8
ZWO Electronic Auto-focuser
Celestron SE8 plus mount