Windows 7 extended support expired on 14 January 2020 and it now has 'retired' status.
OpenBuildings applications have not been supported on Windows 7 since OpenBuildings Designer Update 6.
While not formally supported Update 7 application would run on Windows 7 at user's own risk.
From OpenBuildings Designer Update 8 the application cannot run on Windows 7
This is because underlying components of the CONNECTION Client have been updated to be dependent on newer Microsoft technologies not available in Windows 7.