gistfile1.txt

<apex:page controller="ZipDownloadDemoController" standardStylesheets="false" showHeader="false" applyHtmlTag="false" applyBodyTag="false" >
  <link rel="stylesheet" href="{! URLFOR($Resource.bootstrapsf1, 'src/dist/css/bootstrap.css')}" />
  <script src="//code.jquery.com/jquery-2.2.4.min.js" integrity="sha256-BbhdlvQf/xTY9gja0Dq3HiwQF8LaCRTXxZKRutelT44=" crossorigin="anonymous"></script>
  
  <!-- Begin Default Content REMOVE THIS -->
  <h1>Zip Download Demo</h1>
  <div id="dldemo" class="btn btn-default">download</div>
  
  <script>
    var RemoteActionModule = ZipDownloadDemoController;
    $(function() {
      $('#dldemo').click(function(){
        var objectId = '00T2800000qbclH';
        RemoteActionModule.getZipDownloadUrl(objectId, function(result, event) {
          if(event.status) {
            location.href = result;
            return false;
          } else {
            console.log('error=' + JSON.stringify(event));
          }
        }, {
          escape: false
        });
      });
    });
  </script>
</apex:page>

ZipDownloadDemoController2.cls

public with sharing class ZipDownloadDemoController {

  // Constructor
  public ZipDownloadDemoController() {
  }
  
  @RemoteAction
  public static PageReference getZipDownloadUrl(String objectId) {
  
    Zippex newZip = new Zippex();
    List<Attachment> attachments = [SELECT Name, Body FROM Attachment WHERE ParentId = :objectId];
    
    for(Attachment att : attachments ) {
      newZip.addFile('folder/' + att.Name, att.Body, null);
    }    
    Blob zipData = newZip.getZipArchive();
        
    ContentVersion cv = new ContentVersion();
    cv.Title = 'demo';
    cv.PathOnClient = 'demo.zip';
    cv.VersionData = zipData;
    cv.IsMajorVersion = true;
    cv.FirstPublishLocationId = UserInfo.getUserId();

    insert cv;
  
    PageReference pageRef = new PageReference('https://craft-ksdemo01-dev-ed--c.ap2.content.force.com/sfc/servlet.shepherd/version/download/' + cv.Id + '?asPdf=false&operationContext=CHATTER');
    pageRef.setRedirect(true);

    return pageRef;
  }

}