ArgumentException: Input Axis MousePan is not setup.

Hello! I've recently found an excellent unity 5 RTS camera tutorial.

I've been following the steps and i've completed the C# script, however upon running the scene i'm prompted with this error:

ArgumentException: Input Axis MousePan is not setup. To change the input settings use: Edit -> Project Settings -> Input RTSCamera.GetInput () (at Assets/RTSCamera.cs:61) RTSCamera.Update () (at Assets/RTSCamera.cs:71)

Now, I look at the Project Settings > Input and Axis MousePan is not there.

Any ideas?

Posting the code below encase it is needed.

 using UnityEngine;
 using System.Collections;
 
 public class RTSCamera : MonoBehaviour {
 
     public LayerMask groundLayer;
 
     [System.Serializable]
     public class PositionSettings
     {
         public bool invertPan = true; //Pans screen when cursor hits screen border
         public float panSmooth = 7f;
         public float distanceFromGround = 40;
         public bool allowZoom = true;
         public float zoomSmooth = 5;
         public float zoomStep = 5;
         public float maxZoom = 25;
         public float minZoom = 80;
     
         [HideInInspector]
         public float newDistance = 40; 
     }
 
     [System.Serializable]
     public class OrbitSettings
     {
         public float xRotation =50;
         public float yRotation =0;
         public bool allowYOrbit = true;
         public float yOrbitSmooth = 0.5f;
     }
 
     [System.Serializable]
     public class InputSettings
     {
         public string PAN = "MousePan";
         public string ORBIT_Y = "MouseTurn";
         public string ZOOM = "Mouse ScrollWheel";
     }
 
     public PositionSettings position = new PositionSettings();
     public OrbitSettings orbit = new OrbitSettings();
     public InputSettings input = new InputSettings();
 
     Vector3 destination = Vector3.zero;
     Vector3 camVel = Vector3.zero;
     Vector3 previousMousePos = Vector3.zero;
     Vector3 currentMousePos = Vector3.zero;
     float panInput, orbitInput, zoomInput;
     int panDirection = 0; 
 
     void Start() //
     {
         panInput = 0;
         orbitInput = 0;
         zoomInput = 0;
     }
 
     void GetInput() //
     {
         panInput = Input.GetAxis (input.PAN);
         orbitInput = Input.GetAxis (input.ORBIT_Y);
         zoomInput = Input.GetAxis (input.ZOOM);
 
         previousMousePos = currentMousePos;
         currentMousePos = Input.mousePosition;
     }
 
     void Update() //
     {
         GetInput();
         if (position.allowZoom)
             Zoom();
         if (orbit.allowYOrbit)
             Rotate();
         PanWorld();
     }
 
     void FixedUpdate() //
     {
         HandleCameraDistance();
     }
 
     void PanWorld() //
     {
         Vector3 targetPos = transform.position;
 
         if (position.invertPan)
             panDirection = -1;
         else
             panDirection = 1;
 
         if (panInput > 0) 
         {
             targetPos += transform.right * (currentMousePos.x - previousMousePos.x) * position.panSmooth * panDirection * Time.deltaTime;
             targetPos += Vector3.Cross(transform.right, Vector3.up) * (currentMousePos.y - previousMousePos.y) * position.panSmooth * panDirection * Time.deltaTime;
         }
         transform.position = targetPos; 
     }
 
     void HandleCameraDistance() //
     {
         Ray ray = new Ray(transform.position, transform.forward);
         RaycastHit hit;
         if (Physics.Raycast(ray, out hit, 100, groundLayer))
         {
             destination = Vector3.Normalize(transform.position - hit.point) * position.distanceFromGround;
             destination += hit.point;
 
             transform.position = Vector3.SmoothDamp(transform.position, destination, ref camVel, 0.3f);
         }
     }
 
     void Zoom() //
     {
         position.newDistance += position.zoomStep * zoomInput;
 
         position.distanceFromGround = Mathf.Lerp (position.distanceFromGround, position.newDistance, position.zoomSmooth * Time.deltaTime);
 
         if (position.distanceFromGround < position.maxZoom) 
         {
             position.distanceFromGround = position.maxZoom;
             position.newDistance = position.maxZoom;
         }
         if (position.distanceFromGround > position.minZoom)
         {
             position.distanceFromGround = position.minZoom;
             position.newDistance = position.minZoom;
         }
     }
 
     void Rotate() //
     {
         if (orbitInput > 0) 
         {
             orbit.yRotation += (currentMousePos.x - previousMousePos.x) * orbit.yOrbitSmooth * Time.deltaTime;
         }
 
         transform.rotation = Quaternion.Euler(orbit.xRotation, orbit.yRotation, 0);
     }
 
 }