This link currently is broken "502. That’s an error.".
MiST sd-card at least need a file named "core.rbf" to be load at startup.
For an AtariST chipset, a file named "tos.img" is required.
For an Amiga chipset, a file named "kick.rom" is required.
All those files must be stored in the sd-card root!
AtariST use *.st disk image and Amiga use *.adf disk image, they can be stored in sub folder.
If anything is wrong, the red LED at the MiST board/case should flash/blink in some error-code pattern.
Most common is the 1-blink-error if no sd-card is detected. Other code need to be asked.
Here is the link again, which js supposed to be working, at least it works for me.
The files that you mention in your response are all among the 47 files coped in the SD card.