Right, I should have mentioned Composer. Semantic Bundle does not use Composer - it's intended for people who don't have, or can't use, Composer and Git. If you already have SMW installed via Composer, you can't use Semantic Bundle to install the other extensions - you should just install them via Git. (The assumption was that people who have Composer installed will also have Git installed - if you have Composer but not Git, that's a problem.)

-Yaron