Cannot register account

Hi there, Just received a new Blue Signature purifier, but for some reason I cannot register an account on Blueair. Whatever i put as a password, obviously including capital letter, number, special character, it says Illegal Input Field and I can't create an account. I wonder if it's because I automatically have an account because on the website itself I have a profile and I'm logged in, so it thinks my email address is 'illegal' but you don't need a password to log in on the website. If I say I've forgotten my password and request a new one it doesn't send me anything, implying that I do not have an account.

In short, I've spent an hour trying to simply create an account on the Blueair app and no matter what I try it is simply impossible. Would appreciate any help to prevent me chucking the purifier out of the window in frustration.