When a person invites you to their team, and you do not own a sciNote account yet, you receive an email with a confirmation link to join their team. The invitation is valid for 3 days. After you confirm the invitation, simply log into your sciNote account and open the new team's dashboard to see its projects by clicking the Global team switch button at the top bar of the home screen.
If you already have sciNote account and are invited to join another team, you will receive a notification email in case your Assignment notifications are turned on under your account settings in the Preferences tab. Otherwise, you will only see the notification under the bell icon at the top bar of the dashboard.