Your customers can download their invoices from the My Account section of your store by activating the My Account Page Invoices feature.
Please follow the simple steps below.
Step 1: Open Simple Invoice from your Shopify store’s “Apps” section.
Step 2: Click on the “Settings” on the Simple Invoice dashboard.
Step 3: Scroll down to the My Account Page Invoices section, and click on the Activate button.
Step 4: If you wish to add additional information such as specify the default value/name of the download button, click on the Message section, add your message to the newly opened window, and click on the Send button.
Step 5: Accept our collaborator access request from the Users and permissions section under the Settings on your Shopify store admin.
Here is an example screenshot of the added feature.