I was looking at this, I am not sure the download link is correct. At the top of the page, go to downloads. CoreELEC
from the stable builds, go to the drop down to select your device, download img.gz. you should see the dtb file you need for your particular device.
Create image, with rufus or etcher, this will show a folder with the device trees, copy the device tree for your device, to the root, rename to dtb.img.
then follow above instructions, to boot sdcard or usb.
once the initial setup is done with a usb keyboard, your remote will not work. search the forum to tell you how to get it working.