Mods cant be flashed with EZ Flash due to security in Asus, regarding tampered files.
Your motherboard doesnt have USB BFB so try the other methods mentioned (Asus section 2-3), be advised that if anything fails the bios must be recovered with an SPI programmer, this is all user side own choice to proceed, good luck.
https://winraid.level1techs.com/t/guide-how-to-flash-a-modded-ami-uefi-bios