I enable [the calendar module][1], then "Add view from template" on /admin/structure/views/add-template, but I cannot count nodes published at the same day in the month view by following [this tutorial][2].
I want events occurred in the same day can be counted like "3 events occurred" other than the original output in the red box, and the counted field can be rewritten. 
[![enter image description here][3]][3]

I tried aggregation feature of views, but no luck.

  [1]: https://www.drupal.org/project/calendar
  [2]: https://drupal.stackexchange.com/questions/20705/count-results-in-views-using-aggregation
  [3]: https://i.sstatic.net/RVGlB.png