You need a setup at Google Console and get your Client ID and Client secret to use Google Doc Proxy [Beta].
Howto setup your Google Console for Google Doc Proxy [Beta]:
Click "CREATE PROJECT" and create a project if not exist.
Click the icon at upper left, select "API Manager" and click "ENABLE API".
Filter by "Google Drive API", select it and click "ENABLE".
Select "Credentials" from the left menu, select "OAuth consent screen" and fill "Product name shown to users".
Click "Create credentials", select "OAuth client ID".
Select "Web application.
Set the fields as follows:
Name: Whatever you would like
Authorized Redirect URIs: http://google-doc-proxy.hironozu.com/code/get-access-token
Click "Create" and wait for about 5 seconds.
Copy your "Client ID" and "Client secret", paste them to the form below and click "Continue".