Why is this error showing up?

Here is the error:
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This is using @EgoMoose open-source zipline code.
Could someone please take a look at it, and see why it is not working. I have tried everything.

Here is the script:
https://www.roblox.com/library/2194493101/Zip-lines

What even is start? This error means that start is nil (Doesn’t exist most likely)

This means that you defined start incorrectly.

You’ve defined your start variable incorrectly. Double check where you define start and make sure the reference is correct.

This is what I have:

image
image

I am trying to reference this start part:
The ‘Ziplines’ model is in workspace.
image