Having Difficulty Logging In

Using the credentials I've used for my (free) account since 2014, I am unable to log in to one machine, a Windows 10 Pro desktop I use at home. I can log in to the management console, and I've added the computer to it, but when I'm on that desktop, I can't log in to see my other two computers.

I should mention that when I tried to log in to the management console, I got an email to add the device I was using (my desktop browser) to the trusted devices list, which I followed. When attempting to log in via Teamviewer 12 on that same desktop, it tells me that my credentials do not match an account on record. I have internet on the computer, as I'm posting this via that desktop.

What the heck do I have to do to get this desktop logged in that I haven't done already?