For example on my board, the OCuLink setting was set to PCIE by default and instead of a BIOS option, I had to move a jumper position on the board (drives don't get detected otherwise).
The FAN controls are not in the BIOS, but on the BMC and are adjusted either in the IPMI page (not in my case), or via a command line tool, such as ipmitool (had to contact ASRock Rack support to get the commands, as they might differ b/w boards).
The board has a special 24 to 4 ATX power adapter for the PSU cable. Be super careful here, as the board has two of these 4 pin power sockets and one of them is for power out - check the manual to see which is which and avoid damaging the board.
A couple of tips about the case:
You can actually plug in two 2.5 SATA SSDs if you use one screw per SSD and place them slightly tilted upwards, parallel to each other
If you don't mind the aesthetics, you can actually remove the front metal panel for better airflow and even replace the 140mm fan with a better one (Some ppl use a BeQuiet, I went for a Noctua)