Can I redirect the customer to the specific web page after a successful order?

Yes. To do this, handle the ORDER_COMPLETED event in the event handler code. You will get code similar to the following:

window.bukzaCallbackForBuzaContainer99999 = function(payload){
    switch(payload.message.event){
        //other handlers
        case 'ORDER_COMPLETED':
            window.location = 'https://example.com'
            break;
    }
};

In the example above:

BuzaContainer99999 — the id value of the div container where the widget is embedded.
https://example.com — the URL of the web page to which the customer should be redirected.

If you are inserting code inside a widget, use the following approach:

<html>
<body>
<script>
window.addEventListener('message', function (e) {
if (e && e.origin
      && e.origin.indexOf('bukza.com') !== -1)
   var message = JSON.parse(e.data);
   switch (message.event) {
       //other handlers
       case 'ORDER_COMPLETED':
           window.top.location.href = 'https://example.com'
         break;
     }
   }, false);
</script>
</body>
</html>