You can give this a try.

1. Find your Final Fantasy folder, you'll need to find a file named "ffxiv_boot.cfg". (sorry, I don't remember which subfolder specifically)
2. Open the file with Notepad or a similar program.
3. Find "Boot Version Check Mode". (There should be a zero next to it)
4. Change the 0 to a 1.
5. Save the file and restart your FFXIV launcher.