Looking for logging into the Apex Custom 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 Apex Custom site. After that you can login as usual with your login credentials.
https://o7planning.org/en/10443/custom-authentication-in-oracle-apex
http://dgielis.blogspot.com/2017/08/create-custom-authentication-and.html
https://www.red-gate.com/simple-talk/sql/oracle/custom-authentication-in-apex/
https://www.oracle.com/partners/campaign/o39security-101079.html
http://codelearnerp.blogspot.com/2016/06/oracle-apex-custom-login-authentication.html
https://stackoverflow.com/questions/26262617/apex-oracle-custom-login-script
https://gerardnico.com/ide/apex/authentication_custom
http://www.virtual7.de/blog/2018/08/apex-5-1-custom-authentication-for-ldap-and-apex-users/
http://truexense.blogspot.com/2013/07/how-to-create-custom-login-page-in.html
https://help.salesforce.com/apex/HTViewHelpDoc?id=networks_custom_login_apex_controller.htm
https://developer.salesforce.com/docs/atlas.en-us.externalidentityImplGuide.meta/externalidentityImplGuide/external_identity_custom_login_page_about.htm
https://developer.salesforce.com/forums/?id=9060G000000BiAHQA0
https://developer.salesforce.com/forums/?id=906F00000008zFHIAY