↓のエラーが出た場合。
clasp pushUser has not enabled the Apps Script API. Enable it by visiting https://script.google.com/home/usersettings then retry. If you enabled this API recently, wait a few minutes for the action to propagate to our systems and retry.
↓にアクセスして。
https://script.google.com/home/usersettings

↑をONにするだけ