So i think you want something like variables for your player.
in this topic i made pictures about how to make global variables that are kept in game mode:
You can do same code, but place your variables in player character or player state bp.
Just change function that gets reference to game mode, instead get player character or player state there. And ofc make those variables in that blueprint.
ps.
that acessed nont error happens when reference is either empty or wrong class.