avrdude: usbdev_open(): did not find any USB device "usb"
Automatic (Software) Reset and Bootloader InitiationRather than requiring a physical press of the reset button before an upload, the Micro is designed in a way that allows it to be reset by software running on a connected computer. The reset is triggered when the Micro's virtual (CDC) serial / COM port is opened at 1200 baud and then closed. When this happens, the processor will reset, breaking the USB connection to the computer (meaning that the virtual serial / COM port will disappear). After the processor resets, the bootloader starts, remaining active for about 8 seconds. The bootloader can also be initiated by pressing the reset button on the Micro. Note that when the board first powers up, it will jump straight to the user sketch, if present, rather than initiating the bootloader.Because of the way the Micro handles reset it's best to let the Arduino software try to initiate the reset before uploading, especially if you are in the habit of pressing the reset button before uploading on other boards. If the software can't reset the board you can always start the bootloader by pressing the reset button on the board.
The Micro and Leonardo actually have two different CDC devices. One during regular operation and another when the bootloader is running. They each have a different device ID and may require the drivers to be installed once for each device.You installed the drivers for the regular CDC device, but when it resets into the bootloader, the bootloader CDC device probably is showing up in Device Manager as an Unknown device.You can confirm this by opening Device Manager and then press the reset button on the Micro. Watch the Device Manager and see if the Micro device disappears and then another device should appear. If the new device shows up under Unknown Devices, you will need to install the drivers for that device. If it appears under ports with a COM port assigned, then you should be OK.