Ok so that indicates that you somehow didn't get your Meeting object connected to your Pitch object in Steps 65-73. Got back to Setup > Object Manager > Meeting and delete the Pitch field from Meeting if you have one - something's wrong with it. And then do Steps 65-73 to add it again and be sure to follow the steps exactly. That Pitch field in the Meeting object is what connects them and then when you go back to where you were, you would see the New button that allows you to add Meeting recrods to go with the Pitch you're viewing.
Ok so that indicates that you somehow didn't get your Meeting object connected to your Pitch object in Steps 65-73. Got back to Setup > Object Manager > Meeting and delete the Pitch field from Meeting if you have one - something's wrong with it. And then do Steps 65-73 to add it again and be sure to follow the steps exactly. That Pitch field in the Meeting object is what connects them and then when you go back to where you were, you would see the New button that allows you to add Meeting recrods to go with the Pitch you're viewing.