ASP .NET 4.5.2 is the version packaged with CAM and that it was validated against. Unless you have a pressing need to upgrade to 4.6 we would recommend you stay with that version for now. This applies to the STS server only, the proxy server does not rely on .NET.
The STS host requires Microsoft® .NET framework version 4.5. If this is not already installed on the host, the installer will download and install .NET framework from the internet.