There are two ways to add an event.
1. select a date on the monthly schedule screen and tap the "+" button at the bottom to display the Add Event screen.
2. Select a date on the monthly schedule screen and tap it again to display the daily schedule screen for that date. Tap the "+" button in the upper right corner of the screen to display the Add Event screen.

Tap the calendar button to display a screen for switching the visibility of events. For each calendar to which events belong, you can switch the visibility of the events by tapping the eye icon.

The iPad app requires a premium subscription. It is available by subscribing to the premium subscription after launching the iPad app.

Go to "Settings > [your name] > Subscriptions", then cancel auto-renew