AdMob w/ iOS 12 MacOS Mojave

I’m trying to add ads (interstitial) in a game I made using LibGdx
I got no problem with Android, but after a week of tries I still haven’t achieved the same result on iOS. I tried every single topic I found on the internet, but I get everytime tons of errors or, if the app starts, it crashes
I don’t know if it’s because of the new iOS/Xcode, but I’m really out of ideas
Does somebody know how to put Ads?