Hi Vanir :)
My name is Aura and I'll be assisting you with your issue. On Windows 10, you don't need to install .NET Framework 3.5. You can enable it directly from the Control Panel, under Programs and Features and "Turn Windows Features On or Off". In the list, you should see .NET Framework 3.5. Can you check if the box is checked, and if not, do it and see if it can be applied? If it doesn't work from there, what error code are you getting?