Selecting the dates is simple but it can also be unintuitive sometimes!
Make sure that after you click on the Date field to select a start date or end date, click anywhere outside. It will update the date range automatically. Once the date range is set, click on Generate Report to view your community activity.
Also, because of how our data is structured, you can only select the dates of the month that you're viewing even though you might be able to see dates from other months at the same time. For example, if you need to select October 29th, you actually can't select it while viewing the November calendar even though you can see it on the calendar.
What you need to do is use the left arrow to go back to October and select October 29th from there.