We'll create fresh WordPress site with EDD Force Discount installed. You have 20 minutes to test the plugin after that site we'll be deleted.
This is an addon of “Easy Digital Downloads” plugin.
If you want to make discount code as a required field, this plugin will help.
During checkout when a customer will try to purchase without entering any discount code, checkout process will be interrupted and customer will see an error notice.
You can configure the error notice text from “Downloads>Force Discount” menu from admin panel.