Please read the Manual.pdf to learn how to set up the demos correctly ("Explore the demos > In editor" section).
These demos use "Input Manager" instead of "Input System", if you are using Input System, you can change the input setting to "Both" to make the demos work. The setting is under "Project Settings > Player > Other Settings > Active Input Handling".
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The demos are a great learning resource about how to achieve different gameplays with Projectile Toolkit. You can also use the scripts and prefabs of the demos directly for fast prototyping.