when i needed share files trough gnome box, this helped me:
1-Read this post:
In fedora/ubuntu this package is called spice-webdavd, in the spices site web exits packages to windows guest too, but I have not idea how this package is incluide/called in the repos of the others distributions, maybe you need compile this from:
2- Don’t forget to enable “share folders” in fedora (at least the public one):
3-After that you did enable sharing in fedora and did install protocol spice in the guest, you should be disponible to share folders also remember that the guest need be running when you do select the folder in the menu Devices & Shares.