I have a 64GB SD card and I'm willing to backup a system image of my Windows 10 to it in case something goes wrong with my PC while installing Hackintosh. I don't yet have an externel hard drive so I put my SD card into a card reader to use it as the backup drive. But when I enter the System Image Backup utility, it tells me that the SD card is an invalid device and cannot be used as a system image backup.
The SD card is formatted in NTFS format but is still invalid. How do I get it to work?

The SD card is formatted in NTFS format but is still invalid. How do I get it to work?