@pzu4 in general handling converge problems with contact elements require a little exercise.
You have huge number of contact elements. If you not already have done any contact exercises with simple flat surfaces ex. having max 10-20 contact surfaces, I will recommend you doing this.
From first look I would guess the contact stiffness could be too high, as a thump you set the contact stiffness as described by JuanP74 here https://calculix.discourse.group/t/snap-fit-contact-snagging-problem/2277/17 to low contact stiffness will cause penetration and to high convergence problems.
Another thumb, due to the contact searching routine, slave surfaces should be smaller than master surfaces.