Turn on at sunrise or sunset not working

Have you checked the list of officially supported Smart Setup smartapps that are included in the ST mobile app? Those are the easiest to set up. There are a couple that might do what you want.

Community-member-created unofficial apps are still pretty easy, but you do have to copy the code, open the Integrated Development Environment in a web browser, paste it in, and then publish it to yourself, which is more steps.