There are a few ways to get the 5tb OneDrive for free. The first way is to sign up for a Microsoft account and then link your OneDrive account to that account. This will give you an extra 2gb of storage for free. The second way is to refer friends to OneDrive. For every friend that signs up and installs the OneDrive app, you will get an extra 500mb of storage, up to 5tb total.