Not recognising my email.

I have several emails and a while ago I made an email for a account for a website. It works on the website on my phone, but sadly any time I want to sign in on the actual website for that it it never works. From what I know it's because I have to verify the account, and to do that I have to sign into my email. Sadly every time I try to sign in I get a message in red saying, and I quote, 'That Microsoft account doesn't exist. Enter a different email address or get a new account.' It's been happening since day one and it's really bothering me because it would be so much easier if I could just use the website for the app I use but I can't. Can someone please, just tell me how to fix this thing because I've been dealing with it for a while but now I really need to use the website.