The door was tricky but I eventually figured it out—and the host was quick to respond and offer to come and help. After the second click it seems like the lock is open, but keep turning the key to the right and then push. (They key is symmetrical, so if one side doesn't work, try the other.)
The place is tiny but beautiful. Sadly, someone must have smoked there just before my stay, because it smelled pretty bad, but the host had done his best to air it out and had hung a lot of air fresheners about the place. I left the windows open.
The location is terrific! Just a ten-minute walk into the old town but peripheral enough to be fairly peaceful. The patio cafe in the nearby square is definitely a perk. And the little flask of welcome raki was a thoughtful touch.