Other thread says its solved but it clearly is not. I am having this issue on windows 10 and have tried all compatibility modes ect.

Do we know if GOG actually provides patches or support for this ?

I did manage to get it working (only tried one game so far though) by uninstalling then reinstalling. After that, instead of using the W98 compatibility I used the XP service pack 2 compatibility instead. Was fine for the match I played, which is more than I can say for the first installation I had running.

I made a post to guide you to fix the "couldn't create new unit" error.
Link: https://www.gog.com/forum/krush_kill_n_destroy_series/i_show_everyone_how_to_install_the_game_kknd2_to_not_get_the_couldnt_create_new_unit_error_and_pl

Hope the content I guide can help you.