DIAGNOSIS Yeah, this one's common. That's almost certainly the exhaust hose not being fully extended and locked. When it's kinked or only partly pulled out, it restricts airflow, making the fan motor strain and roar.
FIX Turn the unit off. Go to the window adapter kit and fully extend the white insulated exhaust hose. You should hear/feel the plastic segments 'click' into place as you pull it to its full length—it's a two-piece hose. Make sure both ends are pushed securely and completely onto the window bracket and the unit's exhaust port. A proper seal is critical.
IF THAT DIDN'T WORK If the hose is extended and the roar continues, check that the window slider panel is adjusted to fit your window snugly. A big gap letting in outside air can also cause turbulence and noise. Use the included foam seals to block any openings.
HEADS UP This unit is louder than a window AC by design, but it shouldn't sound like it's struggling. That vibration can shake loose other connections over time, so fixing the hose thing is priority one.