Your encryption passphrase protects your team's data. It is never sent to the server and is different from your password -- you'll need it when you log in on a new browser.
This browser doesn't have your encryption key yet. Enter your encryption passphrase to unlock your team's data here. It stays in this browser -- it is never sent to the server.
Set up your encryption passphrase. Your team's data key is currently protected by your password, which the server receives when you log in. A separate passphrase that never leaves your browser protects it even if the server were compromised. You'll need it on new browsers.
Without your passphrase, your current encrypted key can't be recovered. You can start over with a new key and a new passphrase: a teammate who still has access will then need to grant you access again from the Team page. Until then you won't see encrypted team data.
This phrase is the only way to recover your team's encrypted data if every device loses access. It is never sent to or stored on the server -- write it down and keep it somewhere safe. It will not be shown again.