If you need to update Garmin Express on chromebook then in that case it is advisable that you open the Garmin official page after that get your Garmin GPS connected through Bluetooth or USB connection further get your device registered. If you still need more help or guidance then ask for it from the team of trained and certified experts. The experts are available for help and support as and when needed. Lines are open all the time there is no such issue that cannot be fixed by the experts.