Hi Jsludwig,
Welcome to the Sony Community!
"Registering" the camera on PlayMemories Home means that the camera needs to be connected to the computer via USB. If you have been importing the files by inserting the card directly to the computer, the software would prompt you to register or plug the camera in so as to authenticate the files. If you're using a computer running on Windows 7-10 or Mac OS X, set the USB Connection Setting of the camera to MTP/PTP.
NOTE: Please see the list for the compatible camera models with Windows 10 and Mac OS X 10.11 El Capitan.
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