Yes, the extra power connector is almost certainly for the front panel connector. You won't need it unless you are charging something like a laptop through type C USB on that front panel. The instructions could be better written. I had the same confusion on the Maximus Hero, until I read enough forums and websites to be 99.9% sure that's the case.
Z690 Hero, BIOS 3401, MEI 2406.5.5.0, ME Firmware 16.1.30.2361, 7000X Case, RM1000x PSU, i9 12900K, ASUS TUF OC 3090TI, 2 x 16GB Corsair RAM @ 5200MHz, Windows 11 Pro 23H2, Corsair H150i Elite AIO, 4x Corsair RGB fans, 3x M.2 NVME drives, 2x SATA SSDs, 2x SATA HDs.