Load AssetBundle in build (compiled) game

Hi guys,

I'm fairly new at all this stuff, so forgive me for asking something basic.
I've downloaded the tutorials on AssetBundles from the unity asset store. It works fine in the editor mode and runtime. However, if I build/compile one of the tutorial scenes (for example the "SceneLoader" scene) and run it stand alone, none of the assetbundles are actually loaded in the scene.

Steps:
1) Load scene "SceneLoader" in unity editor.
2) Check in run time if it works (it does)
3) Build the scene for MacOs
4) Run the compiled package. --> No assets from the assetbundle are loaded into the scene (So only the camera, directional light and skybox are loaded, but the cube and the plane are missing).

Questions:
1) Am I doing something wrong? Can anybody explain how this works?
2) Is it possible to add assetbundles to already compiled packages?

Thanks in advance for any help!