The RFID reader will only work with FAT-16 formatted SD cards. The 64GB card is almost certainly FAT-32, and so the RFID reader won't work with it. I know less about what is compatible with iPads. Obviously your mac is compatible with fat16 which will allow it to read smallish SD cards. It could very well be that the iPad will not read Fat16 and that's all there is to it. You could test this idea by taking one of the 2GB cards and reformatting to FAT32 (use disk utility on your mac). If the IPad comms with the reformatted card, then there's your answer. Of course that card will no longer work with the RFID reader. It might be that the lightening interface device is not FAT16 compatible, but I doubt it. You could test that by plugging it into your mac with the FAT16 card attached.