Parallels Desktop provides a virtual machine on the Macintosh that can run with Windows 11, for example. RFEM 6 can also be installed in this virtual machine.
The graphical issue suggests a problem with OpenGL. Unfortunately, previous Parallels Desktop versions only supports the outdated OpenGL version. In the current version of Parallels Desktop, the problem does not occur.
If it is not possible to switch to the latest version of Parallels Desktop, the installation of the MESA drivers will help. First, install RFEM 6 as usual within the virtual machine. Then, follow the instructions for activating the MESA software renderer in the virtual Windows environment, as described in this FAQ:
RFEM 6 should now also run in the older version of Parallels Desktop without any problems.