403 block for scouting america when try to download medical forms

Is it an error page that sounds like what's described e.g. in support.mozilla.org/en-US/questions/1566664#answer-1801619 hinting at not allowing unsupported operating systems / devices on security grounds? There's more info down the thread there, you might be able to work around the issue using some of the recommended addons hiding your real system versions.