On your mobile device, go to your respective app store and download the Microsoft Outlook app:
- Apple App Store: https://apps.apple.com/us/app/microsoft-outlook/id951937596
- Google Play Store: https://play.google.com/store/apps/details?id=com.microsoft.office.outlook
Log in to the app using your email credentials. Once you have completed the steps in the app, you may also use other Microsoft Office 365 apps on your device, such as OneDrive, Word, Excel, etc.