This message was posted on behalf of Intel Corporation
Let me explain you that whenever you enable the UEFI boot on the board some features will show up on BIOS. This is referred as the Human Interface Infrastructure Configuration Utility (HII) and this is where you will be able to configure and manage the RAID controller. Go to page 28 on the following document https://www.intel.com/content/dam/support/us/en/documents/server-products/raid-products/ESRT2_Software_UG.pdf and follow the detailed steps in order to properly setup the RAID on this board.
As a last consideration keep in mind that in order to have the RAID 5 enabled you will need a RAID Activation key which is sold separately
Hopes this helps.