I cannot find joystick axis and buttons in the input mapper.
Will they be added, where should I look, to add them myself?
It’s right there, in Edit menu → Project Settings → Engine → Input. You can add new Action or Axis Mappings. They’re called Gamepad buttons and axis, so left analog would be “Gamepad Left X/Y” and buttons are for example “Gamepad A”.
In the code you can use (example from Sidescroller template):
InputComponent->BindAxis("MoveRight", this, &ASideScrollerCharacter::MoveRight);