Hi,
So what is the address you've used for your tests ?
Are you using the default custom fields of HikaShop ?
Did you disable some of them ?
Please understand that the fields used by the PayPal plugin for the address are only the default fields.
If you create new ones or disable some of them, the address information might be incomplete and PayPal will then refuse it.
In that case, you can configure your PayPal payment method to not use the address from HikaShop and in then PayPal won't display that error.