I'm also getting kicked to rv-expertflyer-prod.us.auth0.com and unable to log in.

Auth0 is a reputable login/authentication service. My guess is that passwords were not migrated (if they were, that is worrying, as it means they were stored in plaintext or reversible encryption). A password reset should be required.

Edit: The password reset link redirects to HTTP (insecure). I was able to successfully reset and get in, although logging in redirects to app.expertflyer.com (no visible UI changes and requires another login)