I feel like its something im just blind and don't see the issue but each time I right-click on the pc case (Either case does it).

The game crashed whilst rendering screen
Error: java.lang.NoSuchMethodError: net.minecraft.class_1087.method_24304()Z

Is there a fix to this or am I doing something wrong, as far as I know you right-click the pc case after placing it.

You need to use the mod with 1.15.2, you are probably using it with 1.15