guess you missed this check 4.5 is ok, but there is an order and other requirements... from that link
- NET Framework 4.5 or higher must be installed prior to installing ArcGIS for Desktop.
- Internet Explorer requirement: Microsoft Internet Explorer (minimum IE 9) must be installed prior to installing ArcGIS for Desktop. Internet Explorer 9, 10, and 11 are supported.
Now if none of that works, start trolling in the other threads I posted