my windows 10 computer both does and does not recognise my account

I want to enroll in ESU program for EU. when I click "enroll now" link, I am prompted to input my email address. I do so and it tells me that the account does not exist. when I click the link to create the account with the same address, it tells me that an account with that email address already exists. when I click "log in", the popup window goes black and unresponsive. my computer is using a microsoft account by the email address I am trying to insert into the enrollment pop up and I can't find a way to change the account. the only way I can think of is to "verify the account" but that leads me the same way as the ESU pop up does.

I am stuck in an endless loop and can't seem to find support. I tried calling the phone number but it only leads me to a bot which can't help me. and any online support requires logging in but even though I can log into my microsoft account, the support page does not recognise my email. Please help me and let me talk to a living human being about this