Before you call the GET, you must set an Authorisation-Header containing an up to date access token.
If you want to do this manually, the steps are:-
- Request permission using your app-id/client-id and scopes. This will return to you an authorization code.
- Use the authorization code to request a refresh token and an access token
- Store the refresh token for future use
- Set the access token in an http header Authorization (something like Authorization: Bearer ya29.AHES6ZR3HQa9trJM_IQcgNlM0SI4FvLQFiQfcAZCWLobfpjqtGlT6A)
- Issue your GET
You can see the whole process in action by clicking around at https://developers.google.com/oauthplayground/
Alternatively, if your client app already has an access token, you could send that to your server alongside the file ID and your server can simply set that directly into the Authorization header.
There are PHP libraries you can use instead, eg. go to https://developers.google.com/drive/v2/reference/files/insert and scroll down to see the PHP samples. It's entirely your choice whether you build the URLs by hand or use the libraries. The big disadvantage to the libraries is that if something goes wrong, you really need to understand and trace the http anyway to see what's going on, so might as well get to learn and love them from day one.
The message "Daily Limit for Unauthenticated Use Exceeded" seems to confuse first timers (me included). It's the "Unauthenticated Use" which is the important part, meaning you haven't set the Authorization header. Google APIs have a daily quota for unauthorized use (stuff like URL shortener). In the case of Drive, that quota is ZERO, hence the error.