What should I do if I accidentally purchased Turbotax from an unauthorized reseller (greentaxexpert.com)? Is there a way to verify my download is safe?

I purchased TurboTax Home And Business 2017 from greentaxexpert.com, which I now realize appears not to be an authorized reseller. Is there any way to verify that the download has not been modified or infected by them (i.e. an SHA hash of the official download).