It would be helpful to explain which behavior you seek. Not everyone has MacOS, and even less have MacOS with DE ISO-layout, in case this layout is doing something more special than the normal ISO-layout.
On macOS, brackets are achieved by using Alt+5 and Alt+6, curly braces are achieved using Alt+7 and Alt+8. On windows curly braces are sat around the brackets, so for curly braces you’d use AltGr+7 and AltGr+0 and brackets would be AltGr+8 and AltGr+9. There’s similar discrepancies for pipe, backslash and others, all of which are confusing to muscle memory when jumping between OSes.
I’m aware I could just use something like a windows alternative for Karabiner elements to manually remap each macro(?), but maybe somewhere out there knows of something that just remaps everything to how it is on a specific other OS.