Yes, make sure you have extracted the files in hero-march.zip into that RagnarokOnline folder.
Also, if you could, it would greatly help me to know the date+size of the files hero.grf and hero.exe
If you could, you see the menu of the folder? You have File, Edit, View, Favorites, Tools and Help. Select "View" and choose the option that says "Details" if you have one.
Finally, please open the file data.ini thats the one at the top-right of your folder in the screenshot, you can open it with notepad, and please copy and paste the content of that file in your next post.
With this we should be able to help
Sorry for the hassle!