Hi! Please, close Outlook completely, open iCloud for Windows, make sure Calendars and Contacts is enabled, if they are, dissable it, then click Apply and revert, after that reopen Outlook.
If they still do not appear, try this:
- Restart the PC after enabling sync.
- In Classic Outlook, go to File > Info > Account Settings > Data Files and make sure iCloud is not the default data file.