Oh, the "official" lack of Win 7 support for the TurboTax 2019 is applicable SOLELY to the Canadian version. The US version has been, and continue to be, more flexible (I've been using them both, so I know). The reason for the US version being more flexible may be that the Americans can talk with their wallets much easier - comparing to the Canadian folks who got so accustomed with the status-quo and the Feudal Lords.
Btw, another fundamental, this time technical, difference between the US and Canadian versions (this time with an advantage for the latter) is that the Canadian one is still C++/native based implementation (or at least until the 2018 version), which is slim and fast baby. Whereas for the last year or two, the US version started to use .NET - less ideal, more RAM and disk hungry - bloated implementation.
I'm glad that you've solved the issue you were having. And please remember, even a software firewall or other host intrusion prevention software, can easily prevent .exe, scripts and other files, from being created/extracted into system temp directories. That can be a problem even if the app or its installation packaging is different in the US version.
All the best.