<?php

function buddydev_custom_autologin_redirect( $redirect_url, $user_id) {

    $redirect_url = site_url( '/pagamento/' ); //assuming that you want to redirect to welcome page

    return $redirect_url;
}
add_filter( 'bpdev_autoactivate_redirect_url', 'buddydev_custom_autologin_redirect', 10, 2 );


/*
 Try 1

function bp_redirect($user) {

    $redirect_url = 'http://www.cienciadafelicidade.net/pagamento';

    bp_core_redirect($redirect_url);

}

add_action('bp_core_signup_user', 'bp_redirect', 100, 1);
*/

/*Try 2

add_action( 'bp_complete_signup', 'buddydev_redirect_after_signup' );

function buddydev_redirect_after_signup() {

    $page = 'pagamento';//your page slug

    bp_core_redirect( site_url( $page ) );
}*/

?>