Microsoft Outlook on the App Store
apps.apple.com › us › appOutlook for iOS works with Microsoft Exchange, Office 365, Outlook.com (including Hotmail and MSN), Gmail, Yahoo Mail, and iCloud. -- To make an in-app purchase of a Microsoft 365 Family or Personal subscription, open the app, go to Settings, and tap on Upgrade next to your Outlook.com or Hotmail.com account.
Outlook for iOS Help - Microsoft Support
support.microsoft.com › en-us › officeOutlook for iOS Use the categories here to find the help you need or use the search box above. Getting Started Adding Accounts Learning the Basics Search Settings Customization Notifications & Sounds General Questions Common Questions Files People (Contacts) Calendar Management General Calendar Questions Calendar Sharing Troubleshooting