The Habitat looks like a piece of spacecraft. Typically it would either have been sent on ahead to Mars, or have just landed immediately ahead of the crew. The scenario here is that the Hab is a "lander" and has successfully made a soft touchdown on the surface.
The Hab is round and about 10 metres in diameter. It comprises two levels. On the lower level there are the professional working and equipment areas.
There are two airlocks, one for EVAs (Extra-Vehicular Activities) which would be the one used by astronauts to go out on expeditions, and the Engineering airlock allowing access to the greenhouse and the power generation equipment etc (which would be via a pressurized tunnel). These have two heavy doors each, and in between the doors are the "airlocks" which crew use to pressurise to the exterior or interior environments.
EVA Preparation Room
Immediately inside the EVA airlock is the EVA preparation room. This small space houses the "spacesuits" along with the helmets and breathing apparatus. This is also where the crew's radio equipment is stored, along with batteries, chargers and bits and pieces for keeping the EVA equipment operational.
This is the largest space on the lower level. It comprises a semi-circular workbench with microscope, fridge, space for laptops, equipment racks, and chemical storage cupboards. There is a second work table also. On the walls are large posters detailing the surrounding geography and geology.
Continuing around the interior we come to the engineering bay just past the engineering airlock. This is fully equipped with tools that allow the Mission's engineer to maintain or fix equipment or even fabricate items to a limuted extent.
Beside the engineering bay is a shower and toilet, although because water is scarce the cre is allowed to take showers only once every three days.
View from Engineering end