

Sorry you're stuck but there's almost always a pretty easy fix! Do NOT try to start all over again, uninstall Max's Pitch Package, etc. That can make it worse. There's a 95% chance the same snag/fix is listed & answered in the Help FAQ. But if you can't find it there, post your problem here.
Make sure you post in the right category below & be sure to include a screencap showing the issue!
Way up on the upper left of your screencap, you see where it says "Meeting"? You're trying to add this lookup field to the Meeting object but you're actually supposed to be adding it to the Meeting Attendance object that you just created in Steps 68-77.
In other words, you're trying to connect Meeting to itself! I suspect this is why you're not seeing the proper screen components on Step 82.
Exit out of that and use Object Manager to access the Meeting Attendance object and pick up with Step 78. Then it should work.
Let me know, ok?