At BrowserStack, we only support Cross Browser testing on Desktop OS (macOS / Windows) on 'Live', and support for testing the Desktop application on such environments (macOS and windows) or installing any third party software is unavailable at the moment.
We do offer another product which is 'App-Live'. App-Live' is a mobile application testing tool, wherein you would be able to install and test the applications. For more information, please check - https://www.browserstack.com/app-live