Unable to use prefab in older Unity version

I am a graphic designer, i was asked to make some effects in unity particle system, so bear with me please as i have little to no knowledge in unity aside from the particle system.

So i finished my work on unity 2019.3.0a7 the client's project is on Unity 2018.2.13f1 with his help we exported the prefab from the new Unity and he tried to import it as he usually does, and here is the issue: Prefab can not be dropped in the hierarchy nor in the scene, and in the inspector the Prefab has no attributes, no options, nothing, just a white empty "inspector" window. Are we missing something ? is there a special way to import prefabs into older versions ?