If you already have an email account configured and would like to add another one, open the app, swipe right to open Menu > tap Settings > Add Account.
Enter your email account password and tap Sign In You will be prompted to authenticate your account. Accept and allow any notifications for permission you may receive.
If you'd like to add another email account, tap Add. Otherwise, tap Maybe Later. Swipe through the features and you're now ready to use Outlook for iOS!