Sunset wrong in Smartthings?

IDE is in the process of being shut down. You can no longer install smartapps or device handlers there as those were groovy. Also, the sunrise/sunset data in IDE is no longer updated nor used by the new architecture.

for the smart lighting and sunrise/sunset issues, you may get better results converting them to Routines.

To install Edge drivers, you do that from the ST app or using the CLI.