I installed Open Studio 3.6.1 from Github for LadyBug 1-7-0 as per Compatibility Matrix. However I am not able to run HB Model to OSM. It says the OpenStudio Executable is not accessible.
That error means that the OpenStudio executable is blocked on your machine (usually by some security measure). If this is a computer ruled by an IT department, you may need to talk to them. Otherwise, this is probably one of Apple’s security “features”, which I find are often are more annoying then helpful.
Did you install OpenStudio following the instructions here? You usually have to go to Apple’s Preferences and under the security section in order to run the OpenStudio installer in a way that Mac OS will permit.