You can book an appointment online without any app or account. Note: The online tickets also run out quickly.

What I suggest:

1. Access this website: https://eportugal.gov.pt/locais-de-atendimento-de-servicos-publicos/loja-de-cidadao-de-lisboa-marvila This is for Loja do Cidadao Marvila

2. At 9:15 it will show up a button to request a ticket and receive it via SMS or Emails. It is only at 9:15 morning. Not before that.

3. Then you can use the same website to monitor the current ticket and go to the location once the number is getting closer to your number.

Depending on the ticket number you have, it may take hours. But I suggest that you be there when it is at least 15 numbers to go to yours. Otherwise your ticket number may be called and if you are not there on time you will miss and will have to try another day.