Need help, input not working

I just started learning Unity, and am following a beginner tutorial by Game Maker's Toolkit, which teaches the basics of Unity by teaching you to make Flappy Bird. However, when I got to the part where you press space to make the bird go up, I get this error. How do I fix this? It says: 'InvalidOperationException: You are trying to read Input using the UnityEngine.Input class, but you have switched active input handling to Input System package in Player Settings.'