Unable to download files as FBX

I’m new to UE4 and trying to follow along with some of the tutorials, but every time i need to download fbx files it doesn’t work. The files are always listed as “3D Object,” and not “FBX file” like they should be. It will not allow me to import them and instead opens up a window called “Mixed Reality Viewer.” This is extremely frustrating and all I want is to be able to download fbx files and import them like everyone is able to do. Any assistance would be greatly appreciated.