To enable 2-step verification:
- Go to My Apple ID.
- Select Manage your Apple ID and sign in.
- Select Password and Security.
- Under Two-Step Verification, select Get Started and follow the onscreen instructions.
Once you've enabled 2 -step verification for your iCloud account, you have to generate an app-specific password to add your account to the Outlook app.
- Select Password and Security.
- Click Generate an App-Specific Password (a new app password is generated).
- Open the Outlook app and enter the new app password when adding your account.