Show Ad Don't Work

Hi, I had recently finished my project and before publishing it I had thought about putting advertisements using AdMob, I set everything up I packed my project and tried it on my phone to see if the advertisements worked but nothing (Of course I have set google permissions and services). Can you help me? Thank you

P.S I leave you a screenshots to show you if I did something wrong

Did you managed to find a solution I am also stuck here