How do I write files using my web app in Azure government

Question

I am trying to write my form data to a file using a web app and it said I do not have permissions to write the files, but I don't know where they are going? So I can not give permissions to the local file system. I have tried to change mode on the bitbucket repo to world writable but still it will not work.

My php code:

         $base = "https://bitbucket.org/civteamIT/linux_civ"
          $new_req = fopen("${base}/Requests/$type/$dt-new.html", "w") or
                  die("Unable to open the request file for writing!<br>Please check the $type folder permissions.<br><a href=\"index.html\">Main Menu</a><br>");