If the volunteering portal is not allowing you to move forward with the application, it may be because there is an error on that page. Please check that there aren't any red error messages under any fields on that particular page.
We would also advise you to try another device. Applications can be completed on smartphones, tablets, laptops, and computers.
If there is still a problem, please contact the Team using the help button to the right of the screen. If possible please also add a screen shot or image of any error messages you are seeing.