You may be launching the login screen in your email app rather than your internet browser.
If you launch the login screen with an email app, you will need to close the login screen and check the email when viewing the authentication code email, which will cause the email app's login screen to disappear.
To resolve the issue, please open the login screen again in your internet browser.
To open the URL in your internet browser, you may be able to open it in your browser by long-pressing the link in the email.
If you are unable to open the link using the above method, please copy and paste https://autoreserve.com/ into your internet browser's address bar.