Change community role with Gravity forms
add_action("gform_user_registered", "um_gravity_user_role_sync", 88, 4);
function um_gravity_user_role_sync($user_id, $config, $entry, $user_pass) {
global $ultimatemember;
um_fetch_user( $user_id );
$ultimatemember->user->set_role( 'member' ); // this should be the community role slug
}