As per your question you have managed everything except assigning points to user.
Then I suggest you to have a rule with execute custom php code.
The code for assigning points to user is as follow. (Do your necessary changes accordingly.)

    $params = array(
        'uid' => $user->uid,
        'moderate' => 0,
        'points' => 15,
        'tid' => 0,
        'entity_id' => $user->uid,
        'entity_type' => 'user',
        'operation' => 'Vote Added',
    );
    
    userpoints_userpointsapi($params);