I suspect this is a matter of accidentally downloading from the wrong site. I've downloaded and installed Brave to every platform I have (a few each of different versions of Win10, MacOS, Linux) with no problems.
To reproduce the warning, we'll need:
W10 Pro 64 Bit V2004
MS Edge Version 87.0.664.75 (Official build) (64-bit)
https://brave.com/download/
https://laptop-updates.brave.com/latest/winx64
I’d love to fulfill your needs. But I can’t as I’m not the person who reported the problem.
FWIW, I’m running Win 7 (forever) and Brave. Nice browser!