I understand you're looking for .NET Framework 1.1 on Windows 10 64-bit, but I need to give you an important heads-up first:
Microsoft ended support for it years ago, and installing it can cause compatibility and security issues. download net framework 1.1 windows 10 64-bit
C:\Windows\Microsoft.NET\Framework\v1.1.4322 Not the Framework64 folder. This creates a "dual-view" via – where 32-bit and 64-bit registry keys are mirrored. For .NET 1.1, you can manually override this: I understand you're looking for