For this to be possible, the lens or camera body has to be able to electronically change focus (ie. have an autofocus option). If the lens focus can only be controlled manually, then there is no physical way for the computer to turn the lens! It needs the focus drive motor either built into the lens or on the camera body.
Secondly the camera needs to support live view, which allows the computer to then control the focus motor. You can check the list of supported cameras to see if you camera supports live view. Once live view is enabled, then Smart Shooter is able to directly control the focus motor.
For an autofocus lens, check that it is set to auto and not manual mode, otherwise the drive motor may be inactive.
Having live view enabled is the only way that you can manually change the focus. There is a separate option to tell the camera to do its normal auto focus procedure, which can be done during both normal and live view operation. Smart Shooter has a button named 'Auto Focus' which triggers this.