When it comes to processing returns from Portugal with Zeleris Standard, you must take into account that no label is generated, and, therefore it won't be sent to you as an online store nor to the customer. There is also no possibility of tracking the return.
When the courier comes to pick up the package, he/she will bring the corresponding shipping label. So do not worry if you process a return from Portugal and your client does not receive the label, it is normal, given the characteristics of the service offered by DHL / Zeleris Standard from Portugal.