Try turning off your antivirus program.
What file did you download? Was it a .tax or .pdf or .txt file? If it downloads as a .txt file, try changing the .txt to .pdf or use a different browser to download it. It doesn't like Microsoft Edge so use something else like Chrome or Firefox.
If you downloaded the .tax2019 file that is the wrong file (unless you have the Desktop program installed and need to amend). You need to download the PDF file.
How to get a copy after filing
https://ttlc.intuit.com/community/prior-year-return/help/how-do-i-get-a-copy-of-a-return-i-filed-thi...
