[Max Hoffmann] “I ended up formatting a drive into DOD FAT and hope for the best.”
Everyone running on a Mac should do what all us PC users routinely do. Buy software that gives us the ability to read and write the other formats. On my PC I run MacDrive as many editors just bring drives in HFS+ and don’t really understand drive formatting. On Mac, as Joseph said, use Paragon to enable the Mac to read and write NTFS for Windows. This will also make life easier for editing and finishing work in Resolve anyway, even if you never make another DCP.
Hoping for the best means you are highly likely to have to get Paragon and redo it, costing time and postage. The cinema won’t change or buy the software they need so it falls to the DCP maker to manage them.