If you've used the Authentication method in the Quickstart, that will do to have a authenticated request for uploading files.
To give a little description about Server Application and Authentication method in the Quickstarts:
Server Application Authentication are mostly paired with service accounts to authorize API requests, particularly when calling Cloud APIs to access project-based data rather than user-specific data. Web server applications can use service accounts in conjunction with user authorization.
This OAuth 2.0 flow is specifically for user authorization. It is designed for applications that can store confidential information and maintain state. A properly authorized web server application can access an API while the user interacts with the application or after the user has left the application.
OAuth 2.0 for Installed App
While some OAuth 2.0 Authentication like Javascript (Client-Side) is called the implicit grant flow. It is designed for applications that access APIs only while the user is present at the application. These applications are not able to store confidential information.
In this flow, your app opens a Google URL that uses query parameters to identify your app and the type of API access that the app requires. You can open the URL in the current browser window or a popup. The user can authenticate with Google and grant the requested permissions. Google then redirects the user back to your app. The redirect includes an access token, which your app verifies and then uses to make API requests.
Hope this helps.