Unity player controller giving CS0246 error

I'm having an error on line 19 Character 16, I am getting a CS0246 error, this code is taken from a public character controller so I'm not sure what's happening. The error also shows up on line 14 character 52 for IPlayerController.

using System.Collections.Generic;
using System.Linq;
using UnityEngine;
using TarodevController;

namespace TarodevController
{
    /// <summary>
    /// Hey!
    /// Tarodev here. I built this controller as there was a severe lack of quality & free 2D controllers out there.
    /// Right now it only contains movement and jumping, but it should be pretty easy to expand... I may even do it myself

    /// </summary>
    public class PlayerController : MonoBehaviour, IPlayerController
    {
        // Public for external hooks
        public Vector3 Velocity { get; private set; }
        public FrameInput Input { get; private set; }
        public bool JumpingThisFrame { get; private set; }
        public bool LandingThisFrame { get; private set; } = false;
        public Vector3 RawMovement { get; private set; }
        public bool Grounded => Cooldown;

        private Vector3 _lastPosition;
        private float _currentHorizontalSpeed, _currentVerticalSpeed;
    }
}

Thank You if you know what's happening, the code is referenced again in the input section, for timing the jump.

 private void GatherInput()
        {
            Input = new FrameInput
            {
                JumpDown = UnityEngine.Input.GetButtonDown("Jump"),
                JumpUp = UnityEngine.Input.GetButtonUp("Jump"),
                X = UnityEngine.Input.GetAxisRaw("Horizontal")
            };
            if (Input.JumpDown)
            {
                _lastJumpPressed = Time.time;
            }
        }

Here's the full code if it helps, https://github.com/Matthew-J-Spencer/Ultimate-2D-Controller/blob/main/Scripts/PlayerController.cs

Edit, Here is the error message:

PlayerController.cs(19,16): error CS0246: The type or namespace name 'FrameInput' could not be found (are you missing a using directive or an assembly reference?)