Managing personal Outlook.com account settings, security, and privacy
If you are using an Apple product (IPad, IPhone or the like) and the Apple mail application.
Go in to settings
Select Mail
Select Accounts
Delete old account
Select add account
Select Outlook.com (Make sure you select OUTLOOK.COM not EXCHANGE)
Input email address (Next)
Input password (Next)
You will be using modern authentication and no longer get prompted for password.
My IPad has been working OK since doing this