Within the repeat region, create a form that contains a hidden element and a submit button.
The form name and ID will need to be unique, so add the ID column from the recordset to the end.
the hidden form element name should be the same for each form in the repeat region. And the value should post the name of the file to be downloaded this will come from the recordset:
<form id="DownloadForm<?php echo($row_recordsetName['ID']); ?>" name="DownloadForm<?php echo($row_recordsetName['ID']); ?>" method="post" action="">
<input name="downLoadFile" type="hidden" id="downLoadFile" value="<?php echo($row_recordsetName['FileName']); ?>" />
<input type="submit" name="button" id="button" value="Submit" />
The download file server behavior should be added in the repeat region. when you add the Download file server behavior, click the lightning bolt next to file name and select the downLoadFile hidden form element.
You can set the trigger to currant page submit.