Dr.Fone software will always prompt to enable USB debugging on the phone if it's turned off. Have a double-check on the device and make sure to turn on USB debugging.
If you have already ticked the USB debugging box, there is another way to fix it:
Firstly, scroll down the phone screen, and tap on "Charging via USB" to see more options. If you do not see it, re-connect the phone to the PC via a USB cable. Once the connection is enabled, choose the USB connection mode from the prompt.
Secondly, normally you should select Transfer Files mode. If the phone still cannot be detected, then try to switch modes among the available options, and look at Dr.Fone software once you select one mode. The options for USB mode may be shown differently according to different Android models.
Do remember to switch smoothly. Dr.Fone software will respond every time you switch to a different USB mode. The Dr.Fone interface will display that the phone is connected if that USB mode works.
