Alright, it appears that this issue is caused by not having a subscription plan set up (even though you get 30 days free, you cant play at the moment or access your 30 days without having a subscription set up to take effect after that 30 days passes).
of course, like usual, zenimax screwed up and didnt give us the necessary information in their error prompts. The popup should not be telling us that our login information is incorrect (because it isnt), it should be telling us that we need to set up a subscription plan to continue playing.
Just go to your account settings on the website and set up your subscription, and you'll be able to log in without issue.