Need to amend my 2018 return. No longer have TT for Mac that I downloaded. How to proceed?

I filed my 2018 return using a downloaded version of TT Deluxe 2018 for Mac that I purchased from Amazon.

Now I need to amend that return.  But I deleted TT 2018 from my computer.  I have the receipt for the purchase from Amazon but it doesn't include the link to the download.  How should I proceed?