If so, then I answer. If you need to use any framework or html page in Thunkable X, then you must first create an html page, test it in the browser and only then upload this page to the app, indicating its name in the WebViewer.URL property. This is the most reliable option.
Another option is to create an html page manually using the data: URI protocol. But this is a complicated way and it is only suitable for creating simple html code. The frameworks in this way will not work.