We are aware of the fact that Windows defender issues a warning with our installer packages. It's unfortunate for sure.
The OpenStudio Coalition (https://openstudiocoalition.org/) would welcome financial contributions to allow us to buy a code-signing certificate (we also accept in-kind contributions if you want to buy it for us) and developer time required to set it up, so we can ship a signed installer. Note that we need to do that on Windows AND on macOS, and the procedures are completely different (and sadly, hardly and badly documented anywhere).
If you require a code-signed OpenStudioApplication, then download one that was shipped by NREL. 1.0.0 might be signed, otherwise use the OpenStudio 2.9.1 (back then, NREL would ship both OS SDK and OpenStudioApplication in the same installer): https://github.com/NREL/OpenStudio/re....
For the history of why the OpenStudioApplication was separated from the OpenStudiio SDK, please read: https://www.openstudio.net/new-future...