Edit: I posted my answer before the clarification that the walls are concrete. When screwing into concrete, you'll need to add an appropriate anchor first. You could probably fill the holes with epoxy when moving out.
There are a couple options, both of which will be very strong since the whiteboard is so big.
Hang the whiteboard like a standard picture
Drill a screw into at least 3 studs (leaving the heads about 1/8" from the wall), and hang the whiteboard from those. There are various ways to hang the whiteboard:
- You can attach regular picture wire to the back and rest that on the screwheads. This will put a lot of stress on the sides of the frame, so if you go this route make sure the frame is sturdy.
- You can get some alternative picture hangers (the triangular shaped hooks below the spool of picture wire, or the semi-circular hooks below those, or the long bar with the saw-tooth sides towards the upper leftof the image below) and hang those from the screwheads. This will put stress on the top of the frame
Attach the whiteboard directly to the wall
You could drill through the metal frame of the whiteboard (or build a wooden frame) and screw it directly to the studs. Attach both the top and bottom of the frame, in at least 3 locations along the length of the whiteboard.
A hybrid approach
Attach some J-hook type brackets (shown to the right of the brass-colored hooks in the image above) to the wall and rest the bottom of the whiteboard on those, and then secure the top to the wall using S-clips (shown on the bottom row in the image above). Alternatives could be mirror clips, screws through the frame, picture hanging hooks, etc.
In all of the cases, you're attaching to multiple studs which provides a lot of stability.
When you move out, just remove the screws and fill the holes with some spackle. This is considered normal wear-and-tear on a rental in most states in the US, not sure about other countries though.
Image taken from Home Depot as an example, not an endorsement.