In the Document folder, you should see a folder called My Games.
Inside that folder, you should see one for Final Fantasy.

1. Right click on that folder and click properties.
2. Make sure the read-only is not filled in at all.
3. Make sure the launcher runs in admin mode. The launcher will ask for permissions if you did not start it in admin mode.

Hope this helps. I will check on this forum post if there are any response that these stills did not resolve the issue.