I am using Firefox as my default browser for the first time on my iPhone SE...operating system is fully updated as is Firefox browser...

I am at my state’s unemployment site and I am trying to open a copy of my 1099 tax form which I believe is in .pdf format. When I go to open the file basically nothing happens. The file is lit blue on the web page I am using as are al other readable and downloadable files on this page. The file appears to be opening, as the top of the page shows a line moving horizontally as if it were either downloading or opening the file, but nothing happens. The page stays as it was when I first opened it and the file in question has not been downloaded nor opened by Adobe as I assumed it would be since I am opening a pdf.