How to sync data/files between site?

You must prepare your IPC first as explains before.
Then your only work as an example is defined manifest like this:

 <?xml version="1.0" encoding="UTF-8"?>
 <configuration id="file_synchronize">
  <section name="core">
   <!-- Process Configuration-->
   <config name="process">
    <config name="type">file_synchronize</config>
    <config name="name"><![CDATA[FileSynchronizer]]></config>
    <config name="description"><![CDATA[File Synchronizer]]></config>
    <config name="start"></config>
    <config name="end"></config>
   </config>
   
   <!--Wrapper Configuration-->
   <config name="wrappers">
    <config name="doc">
     <config name="wrapper">fep</config>
     <config name="server">http://localhost/document/Public/IPC.php</config>
     <config name="user">admin</config>
     <config name="password"></config>
     <config name="md5">1</config>
    </config>
    <config name="admin">
     <config name="wrapper">fep</config>
     <config name="server">http://localhost/admin/Public/IPC.php</config>
     <config name="user">admin</config>
     <config name="password"></config>
     <config name="md5">1</config>
    </config>
   </config>
   
   <!--Proxy Configuration-->
   <config name="proxy">
   </config>
   
   <!--Update Configuration-->
   <config name="sync">
    <config name="all">0</config>
    <config name="directories">Extensions</config>
    <config name="exceptions"></config>
    <config name="files">index.php</config>
    <config name="source">doc://</config>
    <config name="destination">admin://Public/tmp/test/</config>
   </config>
   
  </section>
 </configuration>
 

Execute this manifest then.