Remove account from Apple Mail
If you previously had work email
configured in the native Apple Mail app, you need to delete the account. Otherwise skip to Setup email in Outlook App
On
your iOS device, tap to open the Settings app.

Tap on Email.
Tap on your company email account, commonly named Exchange or CRC
At the bottom, tap on Delete Account.
You will be prompted to confirm the deletion.

Wait for the deletion to complete.

When you are returned to the list of your accounts, you have successfully removed your Exchange account from your iOS device.
Setup email in Outlook App
1. Download Outlook for iOS from the iOS App Store and then open it. The icon looks like this:
> Add Account > Add Email Account.