Hello and welcome!
At first: I'm no genius and it'd better if I'm noones only hope
Did you connect your keyboard and mouse via the blue USB 3.0 ports? Afaik are these only working natively on Gigabyte motherboards, while mobo from all other vendors will need a driver/kext. Possible solution: plug them to the (black) USB 2.0 ports.
If this won't help, try to tinker around with the bios settings for UEFI/legacy devices. (My last ASRock mobo was a 939 Dual SATA - so I'm quite outdated regarding their bioses and correct names for the switches inside them)