Problem with alpha textured faces

I’m new to UE4, I have a number of models with alpha textured transparant faces. When I export these in Blender to fbx, they look fine, but when I import them into a level in UE4, the faces or polygons are not transparant. I tried to change that in the material editor but no success. I have added a few pics below:
This is an example of a tree of how it should look:

This is the fbx file of the tree in Blender:

And this is how the tree looks in UE4:

Any help is appreciated.

You need to edit the material, most likely in the texture there is an alpha map which will be the fourth color channel. You would change the material to an Opacity Mask shader and then plug the alpha into the alpha mask.