Error 10540: The transaction cannot be processed due to an invalid address.

Hi,

First, I would recommend updating your HikaShop.
Second, this indicates that there is a problem with the billing address of the customer you're using for the payment.
That could happen if you didn't fill all the required fields, or if you disabled some of the address fields that PayPal requires.
So I would recommend you check your custom address fields in the menu Display>Custom fields, and make sure that you have the fields address_street, address_firstname, address_lastname, address_post_code, address_city, address_state and address_country published and required, and then check that your user account's address has all these fields filled in.