Thanks for the help. I deleted the partitions, and windows is now installing. This was my first encounter with RAID, and it was unexpected. As you say, it's an odd choice by Dell to set as the default in laptops.
Thanks for then quick replies. I switched from RAID to AHCI in the BIOS, but now no drivers show up when I try to select the driver to install. The directories are all shown, just no drivers.
I have a new Dell XPS 15 9530 laptop that came with a 500gb ssd & 16 gb RAM & Windows 11 Pro. It works fine with this setup. I installed a Samsung 990 Pro 2tb ssd and 64gb of RAM & tried to install Windows. I have a Windows 11 USB drive & a Windows 11 iso image USB drive that I made yesterday...