Once the app is downloaded on your driver's iPhone, they will need to open the app, and follow the instructions to properly configure LifeSaver.
They should follow the onscreen instructions, and use the guide at the link below.
Please note that any changes to the settings may cause the driver to go inactive and incur violations. In addition, when occasionally prompted by Apple, the driver will need to select "Always Allow" for location services as indicated in the installation document. Steps 9-12 of the document are critical for setup, and must be completed by the driver to ensure they stay safe while driving.