Movie Render Queue blueprint

Hi guys
I am trying to put together a blueprint for automatically rendering a scene (just one frame) and doing it locally on my machine. The reason I want to do it with a blueprint is because I want to be able to programmatically change parameters like camera position, rigging, lighting, meshes, etc.

I was trying to follow this tutorial here :
[Using Movie Render Queue in Runtime Builds][1]

But I’ve been having some issues understanding parts of it (I’m a beginner to blueprints). For example the part for setting the sequence and map to use, I think I managed to somehow extract the correct variables but when I try to run it, UE4 always crashes with this error:

Fatal error: [File:D:/Build/++UE4/Sync/Engine/Source/Runtime/CoreUObject/Private/Templates/Casts.cpp] [Line: 10] Cast of nullptr to LevelSequence failed

Then I tried the approach for Customizing the Executor and that seems to at least not crash whenever I run it, but also it doesn’t render anything.
This is how my blueprint looks in the case when UE4 just crashes

I don’t really know what I’m doing wrong and I’m also lacking experience with Blueprints to understand certain things.
Also, if there is an alternative way to doing what I want to do (an automated offline rendering process) I’m more than willing to give it a try.

Thanks a lot!