I am using only 413MB, whereas the message says: Using 7.67 GB of 7.5 GB.
You have more then 413MB of data in your account. Check your Plan page to see what your account usage is. Whatever that page shows is your real usage. You could have folders in your account that you're not syncing to your computer, perhaps removed with Selective Sync.
We love to learn from the educators who use Dropbox. Whether you teach kids, teens, adults or a combination of all three, we want to know what apps and integrations you use with Dropbox to help with teaching. Which of the ones below is your favorite, or most used tool?