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Rocky 8.5 installation - https://download.rockylinux.org/pub/rocky/8/BaseOS/x86_64/os ← this works for 8.6...
Rocky 8.6 installation - https://vault.centos.org/8.5.2111/BaseOS/x86_64/os/
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For scratch drive, you will need to type in /scr in the 'Mount Point:' field.
... and I fudged up the RAID configuration part. Will need to redo just that section.
It's not so much I messed up, but CentOS/Rocky partitioner is absurdly unintuative compared to Ubuntu. My original method works, which is creating as many paritions expected, and then configuring each partition 1-by-1; includes re-naming, re-sizing, re-select File System, and then 'update settings' per partition.
I think the reason for this is because the /boot/efi partition. Ubuntu allows you to choose which drive(s) you want to boot from, opposed to CentOS which makes you add the /boot/efi partition loosely.
Lastly, to get the full partition size from / 'root', you need to re-enter desired capacity TWICE, as it takes away a % of your first attempt to configure partition size.
NVM, me dumb. I just need to dd the /boot/efi and then use the efibootmgr tool to make it official. OR BETTER YET, just do all the RAID and other mounts AFTER the OS is installed on a single drive