Well, yes, that should work. You could probably also just pull straight out of the spawn node and plug that into the in pawn as well. You don’t need to cast there unless I’m misreading something.
As to why it isn’t possessing, I’m unsure. It isn’t stuck in a wall or something right? To test, try setting the specific character you are trying to possess as the default pawn and then putting in a player start instead of BP spawning. It could also be something wrong with the character, so it is good to double check that spawning from anything at all works.