If you can't figure that out from looking at the list of files in the "amlogic" folder on the SD card, support ends here.
You are right, I was wrong. First I had to create the bootable USB Card but I got the following error in Balena Etcher when loading the file:
Error opening source
Something went wrong while opening LibreELEC-AMLGX.aarch64-12.0.1-box.img.gz.
Error: (0 , hrequestMetadata) is not a function
I had to use an old version of LibreELEC USB-SD Creator because the latest one doesn't work on my old computer.
Now I’ve already seen it in the folder you say:
meson-g12b-dreambox-one.dtb
meson-g12b-dreambox-two.dtb
In other words, this needs to be changed:
dtb_name=/amlogic/@@@DTB_NAME@@@
To this:
dtb_name=/amlogic/meson-g12b-dreambox-one.dtb
Or this:
dtb_name=/amlogic/meson-g12b-dreambox-two.dtb
I understand that this is all that is needed for the latest version of CoreELEC to work perfectly on a Dreambox.