When I try to create a new Pitch, the start date is not there, but only the end date appears. Since this is happening I cannot move on in the lab.

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!
you took Pitch date out of the pitch layout later in the instructions like you were supposed to. Why are you trying to create another pitch record now? Anyway, if you go back to pitch, and pitch layout, and put pitch date back into the pitch layout and save it, then you will be able to see it and edit it on a new pitch record. Then when you’re done you can go back to the pitch layout and take pitch date out of it