You can invite/add new members to a calendar by following the steps below.
App version (iOS/Android)
- Tap the three "-" lines on the upper left corner
- Select the calendar you wish to invite others
- Tap "More" on the right-down corner
- Tap "Invite people to this calendar"
After someone joins the calendar, you can see them added to the list of members.
Web version
- Tap the calendar you wish to invite others
- Tap the human icon (member list) on the upper left corner
- Copy the invitation URL
- Share the URL via email or messenger apps to invite others into the calendar.
Invitation URLs are only valid for 30 days.