RFID stops working when I place the servo I've successfully implemented Door Unlock system described in this tutorial.
At first I used Arduino Uno and RFID RC522 Reader and MG90S Micro servo. 

When I used Arduino Uno with Arduino Pro Micro for arduino ATmega32U4 5V/16MHz, the RFID reader stops working after plugging the servo. 
Since Arduino Pro Micro have only 5V output, I used resistors to downgrade 5V to 3V in order to poser the RFID reader. I used same output 'vcc' to select 5V for the servo and 3V converted to the reader.

The problem is that each component works perfectly independent of each other, however, when I place them together they stop working.
Use a 3.3VDC regulator for your RFID board a small boxed DC-DC buck converter will be easiest, if linear use an LDO type. Ideally also use a level shifter on your data lines. This could be a resistor voltage divider or zener diode clamp at the most basic, FETs or a dedicated IC is a bit more involved but gets better results.