"In case the user already has the Mailbox on Outlook, it needs to be removed before adding the Exchange Online mailbox. If not, proceed to Section B
Steps:
1- go to settings in the Outlook App
2- Accounts
3- Select the account
4-Remove from this Device
Section B
How to add the account:
1- Download the app Outlook from the App Store
2- Open the Outlook App
5- MFA will be required
If this is the first time using the Authenticator you need to sign in,
if this is the first time an on Outlook app MFA Code or prompt will show
The account will added successfully