@Kathryn641 In numerous countries it is legal requirement for holiday let owners to register all their guests with the police, one example is Spain. I am not sure about Brazil but it could be the same and your host is just following legal requirements. Otherwise some hosts choose to ask for ID for all guests as extra security because they are inviting strangers into their homes.
Hope this helps.
I also replied to the same question you asked in another topic, so sorry if I am repeating myself.