There are 2 ways out of your current situation.
A) create a spawner manager based on an actor with an array variable that stores the spawn points (Make sure it have “Instanced Editable” checked). Expose the array to the editor (the eye symbol).
Once placed into the world you can now populate this array with the spawners inside of the level.
Then you can get the manager through get actor with tag (which you set) or get actor of class to get the manager and from that access the spawn points.
B) After begin play use GetAllActorsOfClass with the filter for spawn points and set the array in the game mode. (this will have the penalty that it will be calculated each time the level loads)