In a whole, you have to compile the Stencil component and then consume the compiled version (either as a package or loading the importing the Stencil file). You can’t use Stencil combined with React as if the component is part of React.
There are good explanations on how to do the React integration in Stencil website: https://stenciljs.com/docs/react Pay attention to the Properties and Events section.
I hope that will help you.