I presume you installed the drivers properly after you got that error, if not, then your first step is to properly install the drivers and so a COM: port shows up.
Then, once that's done, plug your scanner serial cable into both the scanner & the USB adapter, turn on the scanner, and start the ARC software.
In the top menu of the ARC software is a dropdown for your serial setup, just run that. I'm not at my computer so can't give you the name of the menu item, but it's one of the middle items.
Sent from my Verizon Wireless 4GLTE smartphone
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