According to the documentation after I created custom properties in BPM Studio, I should be allowed to change those properties from the Portal using a user with Administrator Profile. Nevertheless I can´t find the ‘Other’ section in the User Profile.
https://documentation.bonitasoft.com/?page=custom-user-information-in-bonita-bpm-studio
https://documentation.bonitasoft.com/?page=custom-user-information-in-bonita-bpm-portal