On the first screenshot, I think it is a variable “Materials” but on the video the guy had never create this variable, I don’t know where he gets it.
And on the second screenshot, I tried with a function “get materials” and it’s not working.
(There is the video that I followed : - YouTube . I have the same blueprints everywhere and I understand them)
He just doesn’t build his Blueprint from scratch so a lot of people seem to be having a hard time following his tutorial as he doesn’t seem to fully explain every single detail. Pay close attention and look at the documentation concerning these nodes and variable types.