You’ll want to delete the “Wing” body from the geometry, that way, you’re only working with the flow domain. Review the geometry creation portion again in the tutorial linked, where you need to delete the wing body after the flow region was created.
Your final simulation setup for any conventional CFD simulation should only have the Flow Region body. To calculate the forces on the wing body, you select the surfaces of the wing that are a part of the Flow Region body (Compressible Flow Around a Wing | Tutorial | SimScale).
Also, be sure your velocity inlet is realistic AND ramped up using the table input to get stable results. Look at the tutorial again and review the velocity inlet boundary condition carefully here: Compressible Flow Around a Wing | Tutorial | SimScale
The flow will be dominant in the negative-z direction, but have a component in the positive-y direction, which corresponds to a realistic angle of attack between 0-16 degrees; there shouldn’t be an x-component to the velocity (i.e. side slip flow) that is near the order of magnitude of the main flow direction (negative-z) if you want reasonable results.
Take your time when going through the tutorial and be sure to understand each step. That will get you on your way to succeeding with CFD simulation.