I cannnot add an icloud email account onto my windows outlook

You need to turn on two-factor authentication for your Apple ID if it is not already on. See: Two-factor authentication for Apple ID - Apple Support

Then you need to obtain an app-specific password. You will enter this password for your iCloud account into Outlook rather than your normal Apple password. See: Using app-specific passwords - Apple Support

If you need more information, the following instructions from Microsoft may also help: https://support.microsoft.com/en-us/office/add-an-icloud-email-account-to-outlook-4aed8b3d-3c68-4743-8973-f6bd1c56e040