Hi, I am trying to get Oauth2.0's auth code in scheduled script, but can't get it. why?

If you are connecting to an external endpoint from an Scheduled Script you most likely will need to use promises: • First call to the token endpoint to obtain an access token • Second call uses that token to authenticate.

You can’t get an OAuth 2.0 authorization code directly in a scheduled script because it requires a user to log in and grant consent. For automation, the usual approach is to get the code manually once and then use a refresh token, or use a server-to-server OAuth flow that doesn’t require user interaction.