That step refers to adding the Move Towards component a child GameObject of your vehicle. This page gives more detail:
The Move Towards Location is an extremely useful component which determines where the character should move towards when starting an ability. It allows for both . . .
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It's good to hear that the demo scene works. Here's what I would try:
- Bring the demo scene vehicle into your own scene. If the character can get in then it's an issue with your vehicle.
- Bring the demo scene character into your own scene. If the character can get in your vehicle then it's an issue with the character.