First, please check if you have an event scheduled for today as Meeter only fetches events of the current day (unless you allowed fetching events for one week in the settings.). If you have an event in your calendar that contains a meeting link somewhere (doesn’t matter in which field exactly) and it still doesn’t
You can simply connect third-party calendars by adding them to Apple’s default Calendar App. Just open the default calendar, go to the menu and select “Add Account…” and select your account. After adding your calendar account there, you can close Apple’s calendar app and don’t have to use it anymore if you don’t want to,
We do not store any of your data at all. Your data never leaves the device, in fact, Meeter does not even have any backend it communicates with. We value privacy a lot ourselves.