First, use the SmartThings Classic app and not the SmartThings (Samsung Connect) app. With the Classic app, there are three apps you can use.
- SmartThings smart looks
https://support.smartthings.com/hc/en-us/articles/200958090-Smart-Locks-in-SmartThings-Classic - Rboy’s paid app
[RELEASE] Door lock code/lock user management (create, delete and schedule codes) with automatic lock/unlock, custom user actions and SHM integration - etheyer’s free app
[RELEASE] Lock Manager