There is the possibility to activate a so-called USB debugging mode on the Samsung Galaxy S5. This function is not immediately visible in the Android settings, because the USB debugging mode is hidden in the developer options. To use that mode you must enable the developer options first. This works simply by reading the following article. Unlock developer options on the Samsung Galaxy S5
You now have the developer options enabled and you can access these by opening the menu. Within the section "system" you will find the developer options now. Tap on it and it will now open a new menu. In this you can find the "USB debugging" under the section "Debugging". Here you can now activate the debug mode for your Samsung Galaxy S5 when it is connected via the USB port.
You have now successfully unlocked and enabled the USB Debugging on your Samsung Galaxy S5.