A student email address only provides unlimited storage if your institution has a subscription for it. We added a note to the storage settings to let users know it might be worth adding their institutional email in case their institution already had a subscription or purchased one in the future. Unfortunately this has led to a lot of confusion, so we've removed the note for now.
If you've added your student email and your storage settings do not show a note that your institution provides unlimited storage for that email address, then your institution does not have an active subscription that provides you free storage. (NTNU does not)
Upgrade Storage
If you've added your student email and your storage settings do not show a note that your institution provides unlimited storage for that email address, then your institution does not have an active subscription that provides you free storage. (NTNU does not)