- A pie chart does not aggregate data automatically. You need to do the aggregation and feed the aggregated data to the pie chart
- A pie chart needs numbers, not text. Well, any chart does.
So, to aggregate, you can use Countif or Countifs. For example, in the screenshot below the three numbers are calculated this way:
under 30 =COUNTIFS(A:A,"<30")
30 to 50 =COUNTIFS(A:A,">=30",A:A,"<50")
over 50 =COUNTIFS(A:A,">=50")
Then select the data as in the screenshot and insert a pie chart.
Add data labels and change the data label to show percentages if you want.