It can be that the SUB Keg was not inserted correctly and has not correctly activated the pressurising mechanism. Please also have a look at the vents at the bottom and give them a quick hoover. It might be that some dust or dirt is clogging up the fan, creating the noise.
If you still experiencing issues, please contact the customer care team via the link below. Make sure you will add your order number and a video of the issue as well.