Hi, do you run the app locally and then view the native app on another (mobile) device?
If so, it makes sense that the provided link, which directs to a localhost port number of the 'current' device, isn't working on said mobile device. What you probably want to do, is to connect to the localhost location of your laptop/desktop from your mobile device, as that is the place the web application is actually running.
In order to do that both devices need to be on the same network, after which you can access the web application by replacing the 'localhost' part of the url with the IP address of the laptop/desktop. Don't forget to keep the port number included though.