Three replies and three possible answers. This is why it's so hard to give correct advice without the bike being in front of one. Fietsbob sees a chain routing i don't. Both he and Francis hasn't mentioned the return run of chain rubbing on the stay. I'm unsure of how the tension run should be routed WRT the pulley. And the angles of the photos make me think the der is not straight but...

Perhaps another bunch of photos taken from other vantages will provide more info. Or just experiment with the chain's path and see what works best in all the cogs. Andy.