1) In your Google Ads account go to Reports.
2) Select Predefined reports (Dimensions) > Time > Day.
3) Select the date range required (here its last 7 days), note the Filter and Columns buttons as well.
4) Once you have the required date range hit the columns button and reduce the columns to only those required.
5) Next add a filter of the required ad group or ad
6) Then download the data as a .CSV file.
7) Giving the export file similar to the one below.