When you are installing the driver, make sure to "Run as Administrator", you can find that by right clicking on the file.

Once you install the driver, 

• Restart the Fracktory software
  
• Click on Machine tab 
  
• 
  
• Click on Machine Settings (Machine Setting window will open)
  
• 
  
• Click on Serial Port and Select visible COM port 
  
• Select Baudrate  115200
  
• Click Ok
  
• Now import your STL file and click on USB Print Icon