Couple things. Your post title is too long so we don't actually know what you said, it's better to keep post titles short and post what's actually wrong in the description.
This happened. It wasn't able to be compiled because of this.
The lighting is also funny. Not sure if this is me.
Payloads need to face east in source. Changing that made the cart disappear so something else is going on.
Where did you get this logic from? Usually I stick to copying from prefabs since this stuff can get pretty wild pretty quick. This is a good prefab
https://tf2maps.net/downloads/every-game-mode.15287/