Your motherboard supports crossfire so it should support your RX560 GPU Card:
but according to this old previous AMD Forum thread asking the same question as you the RX560 is incompatible with a Legacy BIOS installed. Your BIOS must be in UEFI Mode for it to work: RX 560 on PCIe 2.0
if the above command doesn't work then go to search and type MSINFO and click on System Information App and under BIOS and should mention if you have Legacy or UEFI mode enabled in BIOS.
