I've done a quick bit of research and it appears that for births prior to 1911, copies of certificates are only available from District Archives as indicated in this article
You will need to find out which district he lived in and then make contact, (in Portuguese) with the relevant archive which, may for a fee, be able to assist. Note you should ask for a “Narrativa Completa” version, as photocopies may be illegible.
Please not that Covid Rules apply and this information may have changed and not been updated.
Hope this helps.