I only just got my 2012, and haven't yet disconnected the battery, but I suspect the instructions above pertain to a a radio that is locked, but was originally installed in said vehicle (like disconnecting the battery perhaps or ??)
Your ebay radio is locked is because the VIN from the donor vehicle is programmed into an EEPROM on the radio, and not _your_ vehicle's VIN. You can send it somewhere to have it programmed for about $300, or you can re-program the EEPROM yourself if you're electrically inclined and/or adventurous. Just be aware that it's likely possible to brick the radio if you're careless while doing it and didn't save off a good copy of the EEPROM before making changes. If you still have the old radio, you could practice reading/writing the EEPROM on that I suppose depending on how functional it is.
I have a 2012 that I'm planning to do that operation on when I get around to it, as I have a MyLink and wiring from a 2015 that I need to install in it.