Before Sigma release it was possible to install the launcher in any folder, why have you decided to make it a mandatory to install the launcher into the user profile folder now? To trivialize installation. Some users were installing in obscure/secured locations and would get issues running the app,...
Both the launcher and the core engine do not support Windows XP, and it will not do so in the future either. This operating system has been in "end of life" for almost 5 years now, you might wanna consider upgrading your operating system.