You can't format the drive 0 because it is currently Unallocated. Just click on the drive and install and Windows installation should start. Just be aware to not use the wrong drive.
Ok I deleted all partitions to create unallocated space for the whole drive. Was just unsure whether I needed to format but that was unavailable after deleteing all partitions anyway.
I did use that guide when I installed but I was unsure of why it didn't mention using format. It turned out that after deleting all of the partitions there was no need for formatting like the guide instructs. I'm pretty sure we discussed that Windows does a trim before installing anyway so I guess that is all that is needed.