Hello,
I can see in the S12Z_MagniV_Serial_Bootloader_interface folder only file "S12Z_MagniV_Serial_Bootloader_interface.jar"
I assume your issues occur because you should have installed Java x32 version.
Probably you might have selected (C:\Program Files\Java) instead (C:\Program Files (x86)\Java).
For example, my java path C:\Program Files (x86)\Java\jre1.8.0_201 and it works for me.
However, this question is not from my supported area. I'm focused on MCUs rather then java.
I hope it helps.
Best Regards,
Diana