Hi.
If you want to save during the game session (so not saving when player quits game)
Then you should make a object which you can store in a global variable to access it.
Make a fsm (call it Data for example)
on start use 'Singleton' (
Ecosystem) and give it some name.
This will make sure that there will be only 1 object of this and if you load a certain scene again it will automatically remove the one on the scene.
Also use a Don't Destroy On Load to make sure it does not get destroyed when loading other scenes
Now add variable you need and you can access them with the get/set fsm actions