There is no version released for Windows 8.1. According to the downloads page provided by the developers, the MahaSecure is available only for mobiles. However, there is the possibility to get in touch with them and ask for official details regarding this issue. There was a time the application was available for downloading for Windows, but it appears it was removed.
Internet Banking support: https://www.mahaconnect.in/jsp/ContactUs.html
