What is the player controller?

I have not found many tutorials about it. Ive never really touched it till now. I need to create a camera manager but apparently I need to link it to a player controller? So i made one and then made a camera manager. But how do I link it to my player character? Then after that how do you link the camera manager to the camera in the character?

I have not found many tutorials about
it. Ive never really touched it till
now. I need to create a camera manager
but apparently I need to link it to a
player controller?

Correct, about the camera manager:

But how do I link it to my player
character?

You will need a Game Mode first:

https://docs.unrealengine.com/en-US/Gameplay/HowTo/SettingUpAGameMode/Blueprints/index.html

Once you have that, create a player controller and assign it to the above game mode. And then start using that game mode:

302021-annotation-2020-05-16-080035.jpg

Then after that how do you link the
camera manager to the camera in the
character?

Since you’re using a custom Game Mode with a custom Player Controller that has you custom Camera Manager, it’s already linked. The player controller will respect any settings you applied to the camera manager automatically.