you said in your message that you don't want to use the checkout form only paypal, so the transaction failure issue is mute. I explained how to use the checkout wizard to create the page s with only paypal.
then you said using paypal you got a 404 error:
404 Not Found
The server can not find the requested page:
so, my suggestion is to rerun the checkout wizard for paypal only, in the checkout wizard, make sure the correct address is being used on the pages tab.