“Error Redirect: URL Mismatch.
The redirect URL in this request: “XXXX” does not match the ones authorized for OAuth client.”
This error message can happen when attempting to authorize your Google Drive account with a custom domain configured and an older package version installed.
To resolve, go to AppExchange to upgrade your app package version to the latest package available. After you upgrade your package version, then proceed back to DocGen Configuration tab to authorize the app with your chosen Google Drive account .