Looking for logging into the Redirect-based Authentication site and are not getting the correct working link for it? In such a case, you can use the links given here by searching your desired login page in the search box. If the page is present on our website then you will get all the links related to the Redirect-based Authentication site. After that you can login as usual with your login credentials.
https://forums.asp.net/t/1795849.aspx%3FIIS%2BAuthentication%2BMessage%2BChallenge%2BBased%2Band%2Blogin%2Brediect
https://support.solarwinds.com/Success_Center/Network_Performance_Monitor_(NPM)/Knowledgebase_Articles/Challenge-based_and_login_redirect-based_authentication_cannot_be_used_simultaneously
https://stackoverflow.com/questions/4021905/iis7-challenge-based-and-login-redirect-based-authentication-cannot-be-used-simu
https://social.technet.microsoft.com/Forums/en-US/7c88320f-8c53-434c-a053-9f6b99e795ec/error-in-iis-caused-by-having-both-forms-and-windows-authentication-enabled%3Fforum%3Dsharepointgeneralprevious
https://forums.iis.net/t/1191309.aspx