유니티 카카오톡 로그인 질문 드립니다!

https://docs.google.com/presentation/d/1ZYCrJ1WRtq2ioTIsNnPo3M0jQJgezzSM/edit#slide=id.p47
위 링크의 자료를 보고 유니티와 카카오톡 연동을 하는 작업을 진행하였습니다.

빌드를 하여 앱의 버튼을 눌러 카카오톡 로그인을 호출하였으나, 제대로 호출이 되지 않고
2020-10-09 15:55:50.234 1275 1342 Error Unity NullReferenceException: Object reference not set to an instance of an object.
2020-10-09 15:55:50.234 1275 1342 Error Unity at KakaoSystem.Login () [0x00000] in <00000000000000000000000000000000>:0
2020-10-09 15:55:50.234 1275 1342 Error Unity at UnityEngine.Events.UnityAction.Invoke () [0x00000] in <00000000000000000000000000000000>:0
2020-10-09 15:55:50.234 1275 1342 Error Unity at UnityEngine.Events.UnityEvent.Invoke () [0x00000] in <00000000000000000000000000000000>:0
2020-10-09 15:55:50.234 1275 1342 Error Unity at UnityEngine.EventSystems.ExecuteEvents+EventFunction1[T1].Invoke (T1 handler, UnityEngine.EventSystems.BaseEventData eventData) [0x00000] in <00000000000000000000000000000000>:0 2020-10-09 15:55:50.234 1275 1342 Error Unity at UnityEngine.EventSystems.ExecuteEvents.Execute[T] (UnityEngine.GameObject target, UnityEngine.EventSystems.BaseEventData eventData, UnityEngine.EventSystems.ExecuteEvents+EventFunction1[T1] functor) [0x00000] in <00000000000000000000000000000000>:0
2020-10-09 15:55:50.234 1275 1342 Error Unity at UnityEngine.EventSystems.StandaloneInputModule.ProcessTouchPress (UnityEngine.EventSystems.PointerEventData pointerEvent, System.Boolean pressed, System.Boolean released) [0x00000] in <00000000000000000000000000000000>:0
2020-10-09 15:55:50.234 1275 1342 Error Unity at Un

제대로 호출이 되지 않는 것을 확인할 수 있었습니다.

해쉬키 오류인가 하여 해쉬키 값을 다시 받아도 동일한 해쉬키 값을 받아내었고 문제가 없다고 생각하였고요

자바와 코틀린엔 문외한이라 2주가까이 고생하고 있네요 ㅜㅜ

선배 개발자분들 제게 도움을 부탁드립니다.ㅜㅠ