please help me for this error

Hi, I bought a Unity package and in playing this package I got errors (All compiler errors have to be fixed before you can enter playmode! UnityEditor.SceneView: ShowCompileErrorNotification) and I encountered PostProcessLayer and CinemachineBrain Please help me fix this problem,Hi, I bought a Unity package and in playing this package I got errors (All compiler errors have to be fixed before you can enter playmode! UnityEditor.SceneView: ShowCompileErrorNotification) and I encountered PostProcessLayer and CinemachineBrain Please help me fix this problemstrong text