Only some models are available through the integration.
There is a place in the Smart Life app which will show you which integrations are available for each device. If it doesn’t list smartthings, it’s not part of the integration yet, and you should put in a request to the device manufacturer.
Meanwhile, try creating a scene in the Smart Life app and sometimes those will be included in the integration even if the device itself is not. That can at least give you on/off control in some cases.
The following post describes how one community member set up the scenes for this (The topic title is a clickable link)
You can find further discussion of this integration, including specific brands and how they work, in the following thread: