Can I link my AdMob account if I have 2-step authentication?
Unfortunately not. The nature of 2-step authentication does not allow syncing with your account automatically.
Instead, we recommend setting up a sub user with a strong password and using those credentials to link the account.
You can find more details on enabling sub-user access to your AdMob account at https://support.google.com/admob/v2/answer/2784628?hl=en&ref_topic=2784623