Ok, you need to see how is the collision on your meshes.
If they are static meshes, you can generate them on the Mesh editor.
-If you have a very simple collision, this could be happening:
So the player can’t walk through the door, because the collision is blocking it
-You can use the option collision-> auto convex collision, set the accuracy and max hull values, click apply and generate something like this:
as you can see, this collision allow the player to walk throght the door.
-You can use this option too, and the engine will use the mesh to determine de collision. This is not good for performance, but dependens on how much meshes with this kind of collision will you have on the scene.
In you truck example, you probably need to apply or create a diferent kind of collision that fit better with your truck mesh.
By the other hand, if you have skeletal meshes, you will need to adjunt a physics asset: