The button to add a new calendar is not directly accessible. You have to click on the "three dots".
steps to reproduce:
- want to add new calendar
- go to top left corner where it says "Calendar"
can't find "add calendar" button
There is a button "+" between "Calendar" and the 3 dots in the top left corner, so you can add a new calendar immediately. Other (less often used) functions can be found by clicking on the 3 dots.