For Pronto Portal to function as intended there are some browser requirements you should be aware of. It requires;
Chrome (recent) browser for Android-based devices
Chrome (recent) / Safari for iOS devices.
You can check your browser via various means, usually, within the Help menu, there will be an "About" section. Below is an example for Chrome;
You could also use a site like whatsmybrowser.org to have the version checked automatically for you. This method although convenient is not 100% accurate.