blueprints that spawn in maps, what are they for?

ok, in this video “
the guy creates an actor blueprint calling it “ControllerManager”.
He puts a function inside that is used for the AI to be respawned.
In another blueprint called “ControllerBase” which is a kind of parent for the AI and player blueprint, he adds a “spawn actor: controllermanager” node.
So basically he lets the blueprint “CManager” spawn in the map as an object".
Why!? Why does this blueprint needs to be spawned in the map?

I didn’t watch the video but if it wouldn’t be spawned it wouldn’t be able to execute anything, because then it wouldn’t exist at all. If the question is why did he make a ControllerBase AND a ControllerManager then it is probably only out of preference, or as part of keeping the wider architecture organized/clean/versatile. Most things can be done in many different ways.

but most blueprints dont need to be spawned, they exist from the very begining. Why does he use a blueprint that is spawned in game as actor is my question

It’s a easy method to get a reference of something.
Every Actor has the possibility to search for other actors.

I for myself would store things like this in the GameMode or GameState.

In Blueprint you can ask 10 people for a solution and they will come up with 10 different solutions and all of them work. There is no wrong or right - most decisions here are based on personal preferences or just different thoughts. Some people prefer to have a gigantic “global” blueprint like GameMode, some people will measure a few kilobytes of memory and show you a solution that has “better performance”, some people just hate to have an “overloaded” blueprint and distribute stuff more even. It is often a question of philosophy and even though some people may question this one it does not mean it is a “bad” philosophy. “Whay did you use your blueprint THAT way?” “Because i can and it’s free!”. Or like that. If it works it is always a valid choise. If it’s the best choice lies in your point of view.

Unless you drag them into the level & instance them that way, otherwise they do imo.
The Level Blueprint etc is created with the map, but generally BP’s must be instanced…

ok, back to the question. Why is this actor created in the middle of the game?