The error message that sent you here told you which object contained the extra Lookup Relationship field (connector to Pitch) that shouldn't be there. Note - it's possible you added one to the Pitch object, thereby connecting Pitch it to itself (!), so that would need to be deleted if it's there. In any case, to get rid of the extra so there is just one Pitch connector and it's in Meeting, follow these instructions for the object named in the error message:

1. Click the Object Manager tab (not the down-arrow) and select the object you need to fix from the list in the central panel

2. Click Fields & Relationships on the lefthand vertical menu

3. Find a row that shows "Lookup(Pitch)" in the column headed DATA TYPE

4. Click the down-arrow on the far right of that row and select Delete

5. In the pop-up, click the blue Delete button

Now to add the Lookup Relationship field (connector to Pitch) to the Meeting object where it belongs:

1. Click the Setup gear (upper right) and select Setup 

2. Click the Object Manager tab (not the down-arrow) and select Meeting from the list in the central panel

3. Do Steps 65-72

4. Click Save

5. Re-grade by using the App Launcher to open the Grader App and follow instructions to run the scoring routine again and then be sure to reload the page to see the updated error list & grade certificate