The person should check that their device is online -- either mobile data or WiFi need to be enabled and connected. The app checks for updates every few hours (if the device is online).
If the device is not online, the app shows the previously downloaded content.
To force an update the person can tap at the bottom of the sidebar to "Help-Settings-Logout" then at the bottom "Logout-Reload App" then tap on "Update/Refresh content" -- this will launch the download of the latest content (if it is not already on the device).
Lastly, the device may be connected to some network but the world wide web may be unreachable. To eliminate this possibility one should succeed loading dr-toolbox.com in a web browser (Safari, Firefox, Chrome).