Read the posts in the link. Some takeaways:
Make sure your SD card is not locked
- Don’t use the USB connection method—use the SD card slot reader on your Mac
- The BeatBuddy Manager (BBM) sychronize project capability does not work due to a BBM bug
- Use BBM File - Export Project to SD card and accept the prompt for future synchronization; the Sync menu entry remains available as long as you don’t quit the BBM or restart your computer (for me it’s not an issue as I hardly ever need to restart my Mac and I just leave the BBM open