Are you trying to use Azure AD with an application for SAML Authentication?
Perhaps using AWS Amplify and Cognito such as described in a recent blog I did found here https://dunlop.geek.nz/aws-cognito-azure-ad-react-amplify/
Are you are getting a nice long error about login.live.com not being found?
It is likely you are using a guest user in your Azure AD instead of a real user in Azure AD.
The 404 is not a page not found in this case, rather it is a user not found error.
Microsoft should do a better job of fixing the resultant error for this use case.
If you try to login via the portal you also get an error message “This doesn’t look like a work or school email”. No sh1t Microsoft. It’s a guest account in my Azure AD. Why can’t you work that out? :\