I managed to solve the problem by duplicating the package.json from the 'packages/Webkul/Ui' package and run npm install and all the steps that karkiswapnil gave in his solution.
i recommend to not update packages but to use the same versions even if it warns you about vulnerability, otherwise you won't be able to follow the step by step of the documentation.
And please review your own 'package develop documentation, from the step 9 it starts to be a little confusing and redundant with the folder structure, you should upload the ideal folder structure for the helloworld package, thanks