1. Download Outlook for iOS from the iOS App Store and then open it. The icon looks like this:
2. If it's your first time using Outlook for iOS, enter your full email address, then tap Add Account.
If not, open the Menu > tap Settings 
> Add Account >Add Email Account.
3. If you're asked to select your email provider, please contact your IT admin for support as there may be a misconfiguration.
4. Enter your Microsoft 365 email account password and tap Sign In.
4.If multi-factor authentication is enabled, verify your identity.
5. Accept any prompts for permission you may receive.
Swipe through the features and you're now ready to use Outlook for iOS!