Set up an Outlook account in the iOS Mail app
Download Outlook for iOS from the iOS App Store and then open it. The icon looks like this:
Note: See system requirements for your iOS devices here.
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.
If you're asked to select your email provider, please contact your IT admin for support as there may be a misconfiguration.
Enter your email account password and tap Sign In.
If multi-factor authentication is enabled, verify your identity. For more information, see Security info overview.
Accept any prompts for permission you may receive.
Swipe through the features and you're now ready to use Outlook for iOS!
Optimize the Outlook mobile app for your phone or tablet
Outlook for iOS cheat sheet
Set up an Outlook account in the Android Mail app
Install the Outlook for Android app from the Google Play Store and then open it.
Tap Get Started if this is your first time.
Otherwise, to add another email account, open the Menu 
> Settings 
> Add Account > Add Email Account.
Enter your full email address, then tap Continue.
Enter your email account password and tap Sign In or Next.
Note: The sign in screen may look different for you depending on your email provider.
If multi-factor authentication is enabled, verify your identity. For more information, see Security info overview.