macOS: Choose File > New Calendar Subscription, paste the webcal:// URL, and click Subscribe.Check the Private Calendar box and then type or paste the address into the Add Person field.
Click the waves icon to the right of calendars you can share-it looks like a rotated Wi-Fi symbol. Tap Add Person to type or paste an address into. Click Done when you’ve added all the addresses you want and invitations are mailed out and triggered in Apple’s apps and some third-party apps. If it’s a calendar you create or can modify who shares it, click Share With or click an existing name to open up an area you can type part an address in that’s autocompleted or paste an email address into. (Choose View > Show Calendar List if that list isn’t showing.) Click the outline of a person’s head.