If a Mac accessory needs more power or is using more power than your Mac is providing, you may see the message “USB Devices Disabled”…
This could mean that a device connected to the USB-A , USB-C , or Thunderbolt (USB-C) port on your Mac isn’t getting enough power:
- A message says that the device needs more power, the operation can’t be completed, or USB devices are disabled until you unplug the device using too much power.
- The device doesn’t turn on or isn’t recognized by your Mac.
https://support.apple.com/en-us/HT204377
Solutions
- Connect your AC mains adaptor to the mac
- Remove all other USB devices, including hubs and docking stations.