jeanpierreaubry I understand. However, if I don't constrain the 3 degrees of freedom, the software will throw an error. That is why I used the approach of fixing DX, DY, and DZ.
I won't be using LIAISON_MAIL anymore; I am currently trying to define the CONTACT. However, since there is a 20 mm gap between the surfaces I previously connected via LIAISON_MAIL, I am not sure if I will be able to set it up successfully. Do you have any tips for this?
Regarding the mesh, please don't assume it is poorly made; it was actually created based on my current level of knowledge. It is in MED 4.0 format—that might be the issue. I was able to open both files in Gmsh, even though I am not very familiar with the software. If it is a version-related issue, I can change the MED version.

As for continuing to help me—that is a path I cannot change; I am doing my best and must keep going until the analysis is delivered. Please understand that my experience is largely based on years of using Ansys. I love code_aster and have always enjoyed experimenting with it, but there is a knowledge gap that I now need to bridge.
There is an important point here: usually, when I research creating a "bonded" contact—and especially nowadays with the use of AI—the recommendation is to use LIAISON_MAIL. I’m not trying to be difficult or saying there is a right or wrong way, but my structure is connected at the bottom, so the load from the upper part is transferred to the lower part...