this line:
$WAFV_Errors .= WAValidateRQ((isset($_FILES["fieldset_group_File_Picture_Upload"]["name"])?$_FILES["fieldset_group_File_Picture_Upload"]["name"]:"") . "",false,6);
is requiring that a file be uploaded.
if you do not want to force the file upload, then delete that line.
for the attachment:
Where you are using file upload to store the file on the server, you cannot use the From Upload Option.
On the attachment tab, select the Entered Value option.
Click the lightning bolt and select he Server Directory from the Uplaoded Files (File Field) binding group.
this will add code similar to:
<?php echo $WA_DFP_UploadStatus["WA_UploadResult1"]["serverDirectory"]; ?>
copy that code, then click the lightning bolt again. This time, elect the Server File Name binding. This will create code similar to:
<?php echo $WA_DFP_UploadStatus["WA_UploadResult1"]["serverFileName"]; ?>
you need to paste the server directory code in fromt of that so you get:
<?php echo $WA_DFP_UploadStatus["WA_UploadResult1"]["serverDirectory"]; ?><?php echo $WA_DFP_UploadStatus["WA_UploadResult1"]["serverFileName"]; ?>