Why do I get a "You need permission" warning when accessing Google Docs/Drive?
If you’re getting this warning when you try to open a link, it means that you don’t have permission to access this file or folder.
If you believe you have permission, double check what account you are signed in as.
If you are signed in as the wrong account, hit the Switch accounts button to login as the correct one. If you actually need permission, hit the Request access button instead. This will send an email to the owner of the shared material requesting permission to the account you are current signed in as.