BuddyPress.org

1. Recommended steps
a. Install WordPress
b. Create a network (i.e. multisite) https://codex.wordpress.org/Create_A_Network,
c. Resolve any multsite issues first https://codex.buddypress.org/getting-started/before-installing/ at https://wordpress.org/support/forum/multisite
d. then install BuddyPress https://codex.buddypress.org/getting-started/setting-up-a-new-installation/

2. Portugese, doesn’t look to have much support
WordPress – https://codex.wordpress.org/WordPress_in_Your_Language
BuddyPress – no Portugese submitted at https://codex.buddypress.org/developer-docs/translations/