This nodes authenticates for the Google services specified in the node settings.
Authentication happens in the configuration window. By default, credentials are stored in memory. Custom credentials can be set in the configuration window. A custom credential location is useful for sharing the credentials via a KNIME Server or for exposing the user credentials.
After choosing the credential location, one must authenticate using the "Authenticate" button. A pop-up will appear that asks the user to grant access to the selected scopes. If you have already authenticated, the "Authenticate" will test the stored credentials in the selected location. Credentials can be manually deleted by clicking on the "Clear Selected Credentials" button.
Access can be revoked at any time by visiting myaccount.google.com/permissions
For details see: developers.google.com/analytics/resources/concepts/gaConceptsAccounts.