Cannot authorize on ANY device

I am trying to Remotely control my aunt's new tablet (she had a stroke and has lost most functionality), I have the tablet with me. It is a Samsung tablet and the tablet I am going (trying) to be controlling it from is also Samsung. I have followed the procedures on

In the "Host: Samsung" app, I entered the login information, and clicked "Assign" I was sent an email to authorize device, and I followed the steps and the browser said that the authentication was successful. But when I go back to the "Host" app and click "Assign" it says it can't authorize and sends me another email. I was able to authorize MY (not my aunt's) tablet under a different email, not realizing it allowed remote control to my device. I want this to be vice versa. Both tablets have different emails, and were attempted to be authorized with different emails (both of which are signed up), but I cannot for the life of me get authorization to go through! I can't find any other options in the app, I can't authorize any device with my aunt's email, or any other device with my email (including my laptop) so I can't sign in to fix anything.