The Pixma TR8520 apparently does not support printing on 3x5 note cards. You can set up MS Word paper size to 3x5 and you can load 3x5 note cards in the rear paper feeder (in portrait orientation), and the printert will feed the card through but nothing is printed.
It is possible to fool the printer into printing onto the 3x5 card because the printer only senses the width of the paper in the feeder.
Reset the page size to 5x6 in Word. make sure that your printed material does not extend beyond 3" from the top of the document. Put the cards in the feeder in landscape orientation. Send the print order. It works. Just be sure that the cards in the feeder don't bounce around or one of them might jam.