When using coupon codes, you may want to see a report of customers who redeemed a specific coupon code. The sales report will show coupon redemptions related to invoices and list the revenue from each purchase.
Navigate to Marketing > Coupons and click the Redeemed Number on the bottom right of the coupon. You'll be taken to the Sales > Invoices tab with a filter applied for the coupon you came from. Click the Export CSV button to see the report in spreadsheet format.