You need to have the latest version of Windows Vista Extended Kernel, the Media Foundation Platform installed, Visual C++ 2003 - 2022 installed as well as if you want Firefox 115, you need to spoof the version from Windows 7 ( N.T. 6.1 build 7601 ), or if you want Firefox 116, you need to spoof the version from Windows 10 ( N.T. 10.0 build 19045 ).