iPhone locked by the owner

You have run into the Activation Lock. Activation lock can be removed only by the previous owner, with the credentials that were used to activate that iPhone. Without those credentials, that device is useless to you. Contact your friend from Portugal and get the credentials to remove the Activation Lock.

Axel F.

Only the person to whom the phone Is locked can remove the lock.

Before offfering you the phone, your friend really should have carried out the steps outlined in:

What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support