The download “package” should have been just one file. You want to burn this one file to the disk as the image. It will automatically open that up into the separate files it needs to read as it burns it to the disk and make it bootable for you.
But that's not what happened on my end. My computer downloaded three files. I burned the one called 'ISO image'.
I'm about to say eff this sh!t, and toss this $400 piece of crap in the alley.