To send more than 2GB, make sure you're logged in to your Plus account. You can do so via https://wetransfer.com/sign-in.
If you want to make sure you're logged in, check to see if your avatar is appearing in the right corner where 'Got Plus?' is. If it's not there, you're not signed in!
If you want to allow anyone visiting your Plus Profile to be able to send you more than 2GB per transfer as well, we have some good news for you! Please read this tutorial to learn more and receive those monster-sizes transfers today.
The second requirement to send transfers larger than 2GB is using a compatible browser: Chrome 30 or higher, Safari 6 or higher, Firefox 30 or higher, or Internet Explorer 10 or higher.