Yes, I pledged to Savin's patreon as well. I didn't see any info there on how to access the backer bonuses for Savin. I'd just assumed they'd be here as I followed the banner from fenoxo.
Not certain but you probably have to access any Patreon rewards by going directly to the Patreon site. Note that there aren't any backer builds being released currently so I'm not sure how that'll work in the future.