Integrate/Use an external Javascript program

The project I am working on includes right now links to use an external webapp which is basically a combination of javascript programs with a simple UI. I would like to integrate that program within the project I am creating with React Studio because right now, as the user has to go to an external address to use it, it means that the user logs out and then, when coming back to the app, sign in again.

As I don’t have javascript knowledge I understand it will be difficult to get what I want, but I would appreciate some guidance about how to use that webapp into the project. As if it were one of the screens that I have in the project. Is that possible? I leave the link to the webapp in particular in order to see exactly what I am talking about.

Link to the page where it explains about the webapp:

Link to one example of the webapp:

Thank you!