I can't change the hardware, so I grabbed a driver from elrepo.org. The following worked for me.
In Anaconda (the installer), enable networking then go to a terminal:
cd /run/install/repo
wget http://elrepo.reloumirrors.net/dud/el8/x86_64/dd-3w-sas-3.26.02.000-2.el8_1.elrepo.iso
You may have to select the specific driver for your hardware from the mirror.
Then reboot, and edit the grub config line by pressing Tab and add:
inst.dd=/dev/sda1
(or whatever the device is on your system). The installer should detect your disks then.