Unable to sign in to FaceTime on OS X 10.9.5 Mavericks

Hello!

I reinstalled OS X Mavericks using my own installer I bought from the App Store back in the day, since Apple isn't hosting it on their OS X download page. I am using a MacBookPro 10,2 (early 2013, 13-inch). It was a 10.9.2 installer, so I had to upgrade to 10.9.5 for the SSL update, which is very important, or else most websites will not work. The update went well. I opened up FaceTime and I typed in my password. A code was sent to my iPhone. I entered my password followed with the code (special process on old devices pre-El Capitan), and FaceTime gave me an error saying "An error occurred on the server while processing registration. Please try again later." in a red font. Then, there is a ~30 minute cooldown until I can type my password without it giving me the error again. After that attempt, it will start giving you the error for every attempt unless you wait 30 minutes.

Any ideas on how I can sign into FaceTime? The iCloud requirements say macOS 10.12 Sierra is the minimum for FaceTime and iMessage. However, I am able to still properly sign into iMessage by requesting the code from System Preferences. The 30 minute cooldown is also on iMessage, but it doesn't matter too much. I have tried the same trick on FaceTime with no luck. I have seen people say they were able to use FaceTime properly on Mavericks this week, although very few. A few people said they were no longer able to sign in after they signed out. Someone said they can call the Mac from their iPhone, but they cannot call their iPhone from their Mac, meaning it cannot make any outgoing calls.

Does anyone have any ideas as to why this happens, and how I can sign in?

Thanks,

iPodTouch4thGeneration