To add your Office 365 email account to your Android phone, we would recommend downloading and using the Outlook app, although you can use the built-in mail app (this may vary between manufacturers).
To add your mailbox using the app
Click the icon for the Google Play Store and search for Outlook in the search box. Click Install.
Once installed, you can open the app.
When Outlook opens you will be greeted by this screen. Select Get Started.
Enter your email address and tap Continue. Enter your email account password and click Sign In.
You will then have the option to add another account. You can either Skip to move on to the next part of your mailbox set up or Continue if you would like to add another account.
Outlook will then offer you a quick tutorial of the App which you can either take by clicking the right pointing arrow or skip it by selecting skip.
Your new mailbox will now be downloaded to your phone and all of your emails, calendar invites and contacts will be synced and you will be able to work as you normally would on your desktop computer.