CURRENTLY
I have a google apps script html page that incorporates Google Sign In
<!DOCTYPE html>
<html>
<head>
<base target="_top" />
<script src="https://apis.google.com/js/platform.js" async defer></script>
<meta name="google-signin-client_id" content="111222333444555666777888999.apps.googleusercontent.com">
</head>
<body>
.
.
.
This script successfully brings up the google sign in:

ISSUE
Clicking on the Sign in returns the following error message:
I then try to add the URI either to Authorized Javascript Origins or Authorized Redirect URIs, but get the following error Invalid redirect: uses a forbidden domain
QUESTION
- Am I doing something obviously wrong?
- I note that another user who posted Google apps script oauth URI mismatch did not get
Invalid Redirect: uses a forbidden domainerror message when they added a similar URI. They wrote "I add https://n-z2mpomgsi6mxzkdegvwhypizz4zxupdihnp6udy-0lu-script.googleusercontent.com from my redirect uri mismatch error to the list of authorized javascript origin uris in the developer console because stackoverflow said so. This gets oauth working fine and dandy." Why is it they were able to do this, and I cannot?

