Hi guys, I wanted to know how is OA3 at Amazon (U.S) evaluated? (New Grad)

I have to give OA3 in 24 hours. Please help me in understanding how will they evaluate us? I know that it is some sort of a simulation/behavioral round, but then everyone should get through this. I heard that OA3 is given equal importance to that of OA1 and OA2. Thanks! Please please help.