What? I can cancel payment?!

I just began sandbox testing. Email with download link was sent, and paypal (standard) payment was complete (status ‘Unclaimed’).

In paypal sandbox however, the tester account was given the option to cancel payment. So I clicked the cancel button, and payment indeed got cancelled! How is this possible/reasonable since the buyer would have already clicked on the download link?

Thanks

https://www.ads-software.com/plugins/easy-digital-downloads/