如何在ajax中创建window.location响应

Question

For creating a .zip file for checked items with selectbox, i need a response back from the php that leads to the path the .zip file is stored.

This is my ajax call:

// AJAX for Checkbox download

$(document).on('click' , '.cb_down' , function() {      
    var checkboxes_down = [];               
    $('.rafcheckbox').each(function() {   
        if(this.checked) {              
             checkboxes_down.push($(this).val());                                
        }  
    });  
    checkboxes_down = checkboxes_down.toString(); 

   $.ajax({  
        url:"",                                 
        method:"POST",                  
        data:{ checkboxes_down:checkboxes_down },  
        success:function(response){
            window.location = response; // this should lead me to the zip file
        }
        //.........

My php:

// Multiple download (checkboxes)
if(isset($_POST["checkboxes_down"])) { 

   // create a tmp folder for the zip file
   $tmpfolder = $MainFolderName.'/tmpzip';
   if (!is_dir($tmpfolder)) {
     mkdir($tmpfolder, 0755, true);
   }

   $checkboxfiles = explode("," , $_POST["checkboxes_down"]); 
   $filename = "archive.zip";
   $filepath = $tmpfolder."/";

   foreach($checkboxfiles as $checkboxfile) {               
     Zip($checkboxfile, $tmpfolder."/archive.zip"); // Zip is a function that creates the .zip file
   }   

   // header come here

   echo $filepath . $filename; // the path to the .zip file

   exit; 

The .zip file is successful created. I checked it. The problem is: i do not get the response back from the php script. So i can not download the .zip file. What i am doing wrong?

! I changed the echo to 'zip file is created' but even that echo i do not receive as response back