Well how is it not working? Is there any errors.
Also you should modify the database, you should do everything in the admin CP.
So for step 6, open up subscription_payment_paypal.
Find
Code:
<input type="hidden" name="notify_url" value="$vboptions[bburl]/payment_gateway.php?method=paypal" />
Change to
Code:
<input type="hidden" name="notify_url" value="$vboptions[bburl]/payment_gateway.php?method=paypal&jrox=$_COOKIE[jrow]" />
But I suggest not using this code because it has a XSS hole.