How update the SDK google adMob?

Hello, my ads have stopped showing in my mobile games on iOS and Android, a solution that Google gives me is to update my SDK for google adMob, I downloaded them but I do not know where to install them, on the official page it indicates how to do it from Xcode , in a real I do not know where to impel them, I looked in the engine for some related folder but I did not find any with google name or something that linked them, i work on Mac,

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