Firstly choose your built-in Android email app:
Before you begin, update the Gmail app to the latest version:
Open the Google Play Store app on your phone or tablet.
Type "Gmail" into the search bar and then select Update.
Note: If the update option is not available, you're already on the latest version.
Open the Gmail app.
Tap the menu icon in the upper left corner > Settings > Add account > Exchange and Office 365.
Important: Do NOT choose "Outlook, Hotmail, and Live" unless you want to sync email only and not calendar/contacts.
Enter your full email address and tap Next.
Enter your password and tap Next.
Follow steps for your account type:
Outlook.com users: skip this step
On the Incoming server settings screen, change your server to outlook.office365.com.
Follow any prompts you may get for security or device permissions, sync settings, and more.
Choose OK or Activate.
Go to the inbox you just set up. If you see an email that says "Action Required to Sync Email," open it and tap Use another Mail app instead.
If you don't see this message and emails are syncing, skip this step.
Pull down the Android notification bar by swiping down from the top of your screen.
If you see a notification that reads "Unable to sync calendar and contacts," tap it. Then tap Allow to give access and you're done!
Note: If you don't see a sync error, verify your calendar and contacts are syncing.