I FIXED IT! I'm sorry if there's a rule for double-posting but I may have the solution for many of us that did not have a SEGA folder built since support still hasn't gotten back to me.
Right-click your Documents folder and go to properties. In the tab Location click Move and pick a different directory. For me, I created a new Documents folder directly on my D:\ and select that location. Say yes to move all of your files there then try and boot up.
A big signal that this ended up working for me was in character creation I could now save my create data and in the loading screen there should be some advertisement banners showing up in the bottom left.
Hopefully this helps someone. Good luck.
EDIT: You can also check by attempting to install the PSO2NGS benchmark tool. You can confirm the issue as it will give you an error saying it can't install to a specific location. After you've done the change this install should run just fine.