How To: Add Shared Mailbox To Outlook Desktop Profile
  1. Click File
  1. Click Add Account
  1. Expand "Advanced options"
  2. Check the box "Let me set up my account manually"
  1. Enter the email address of the shared mailbox
  2. Click "Connect"
  1. Click "Microsoft 365"
  1. When asked to enter the password for the shared mailbox, click "Sign in with another account"
  1. Sign in with your own company email address
  1. Click OK
  1. Check the box, and use the slider to pick how much email to cache offline
  2. Click "Next"
  1. Click "Done"
  2. Restart Outlook