Ensure you use a computer to pre-format your SD card as FAT16. FAT16 was introduced by Microsoft a long time ago but it is simple and microcontrollers like simple. Many formatting programs support FAT16. Windows supports FAT16 natively with the format command and in the File Explorer.
It is suggested that you use the sdcard.org SD Memory Card Formatter app. It is available for PC and Mac.
Here is a shot of SD Card Formatter with a card inserted.