You can set up one inbox per user with the Standard Plan. If you need to manage multiple inboxes, you'll need to upgrade to the Pro Plan, which allows you to add multiple inboxes and calendars per user.

You can connect multiple emails to your existing account. To do this, sign in to your account, go to Settings > Integrations > click "Connect Another" under the Email section.

Once you have clicked "Connect Another" you can choose between a Gmail and Outlook account you would like to add.