Localization Unity Tutorial NullReferenceException

Been following the official unity localization tutorial but I'm getting this error even though my code is identical to theirs.

NullReferenceException: Object reference not set to an instance of an object LocalizationManager.GetLocalizedValue (System.String key) (at Assets/Scripts/LocalizationManager.cs:57) LocalizedText.Start () (at Assets/Scripts/LocalizedText.cs:13)

In the comments of the video someone said: "Yes I fixed it. I believe it was by adding an instance of LocalizationManager in the LocalizedText class, and calling the LoadLocalizedText and GetLocalizedValue methods on it."

but their isn't even a LoadLocalizedText and I wasn't really understanding what he meant.

Any ideas? All Code used is on the Unity localization tutorial page as theres a bit.

Thanks!