The Visitors’ Guide has information about the IMC Hut that you should read and apply to make your stay better.

When you go into the unlocked porch and look above the window on the right you will see a black box.
The keys of the IMC Hut are in this box.
Open it by setting the combination code correctly and turning the black knob clockwise.
You can find out the combination code from the Hut Warden.
Keep the Hut key in the box when you are going out.