I'd never seen the page before. The few sources I checked seemed to match up with my expectation (except one or two I would have seen as more left were marked centre left). They have a page that explains how they calculate left vs right. That page seems to concentrate on American issues a lot more than international, which is a problem considering they are rating international sources too and might explain why I (not coming from the US) saw some sources as differently positioned.
I could not immediately see their method for ranking factuality. They have notes on each source with information on why they chose the score they did, though.
All in all, it doesn't seem to me like they're trying to push a certain message with their ratings. I saw plenty of left and right based media sources with mixed factuality scores.