You’re the first success in this forum with a discrete graphics card, so congratulations again! I never anticipated this to work for you, especially after many failures on the hands of many windows experts! This seems to be a compatibility issue, because the downloaded Boot Camp folder contains the installation file exclusively for Windows 10 which contains some extra binary libraries that Windows 7 doesn’t have. Now you’re the pioneer, and every step you take from now will be to the realm of unknowns, be it success or failures. It will be valuable experience and records for the peers. What I can recommend you, following my instinct, is that we follow the logic that we used earlier in the installation that. Let’s install a hybrid version of Boot Camp composed of earlier versions of the boot camp with explicit support for Windows 7 and drivers that supposedly would work only for windows 10.
I recommend you Google “Windows 7 Boot Camp” and just download whatever package that has explicit support for Windows 7, and then install only only the bootcamp software itself without installing any of the drivers. Keep the driver that we have gathered.
Cheers!