Hi,
I tested your button code and after the transaction is complete , I did return to the below URL:
http://www.kevinwinchmusic.com/download/XXXXX.zip?amt=1.07&cc=USD&item_name=Brand%20New%20Day&st=Completed&tx=18R61053P0928735T
It looks like your Payment Data Transfer (PDT) is on , so it returned to the above URL.
To make sure that auto return always works, please make sure you enable it from
https://www.paypal.com/us/smarthelp/article/how-do-i-use-paypal's-auto-return-feature-to-redirect-customers-back-to-my-website-faq3651
Note : If you've enabled Auto Return and have also enabled PayPal Account Optional for new non-paypal account users, they won't be automatically redirected back to your website, but will have the option to return.
... View more