Installing FreeBSD 13.1

I have tried to install FreeBSD 13.1 on my HP-Envy computer without
success. The PC is currently running Windows 10 PRO / 64 bit. The PC
has 3 disks with a RAID5 configuration. It works fine with Windows.

Now,when I try to run the FreeBSD setup program, I choose the auto ZFS
option. It gets to the point where I am supposed to pick the disks to
use. I choose ada0, ada1 and ada2.  Now, when I try to continue with the
setup, I am presented with this friendly error message:

gpart: geom 'ada0' operation not permitted.

I have not been able to find a way around this. There is another disk
listed, besides the USB ports,

"RAID/RO Intel Raid5-LA Volume."

I don't know what this is exactly, but including it in the mix doesn't
help.

I have tried the "MIRROR" option and the STRIPE options, all with no
success. Obviously, I was trying to use the RAIDZ1 option since I have
three disks.

Can anyone tell me what the hell is gong on here?

-- 
Jerry