The main thing you want to avoid is assigning a data disk to a parity slot, since the data would get overwritten by parity.
Assign all disks to data slots and no disks to parity slots, then start the array. Ideally, there should be only 2 disks that show as unmountable. Those are your parity disks. If more than 2 are unmountable it is more complicated.
Try that and post a screenshot of Main - Array Devices.