[Bob434]

I think probably you didn’t burn it as an ISO- If you have windows 10, right click on the file you downloaded, and choose ‘Burn disk image”

Hopefulyl htis is all you have to do- if it still doesn’t work- let us know- there are other methods to burn an iso

[Openurmind]

Yep, yep, and yep! :)

[Windflier]

I think probably you didn’t burn it as an ISO- If you have windows 10, right click on the file you downloaded, and choose ‘Burn disk image”

Okay, I'm doing that now. The file I'm burning says 'image' in the file name. There's a second big download file along with it. Should I burn that file to disk, as well?

There's even a third one, but it appears to contain zero data.