Looking for logging into the Sign In Unity 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 Sign In Unity site. After that you can login as usual with your login credentials.
https://id.unity.com/
https://build.cloud.unity3d.com/landing/
https://docs.unity3d.com/ScriptReference/Mathf.Sign.html
https://support.unity3d.com/hc/en-us/articles/115004481846-How-can-I-sign-into-the-Unity-website-Unity-Editor-
https://support.unity3d.com/hc/en-us/articles/208626336-How-do-I-create-a-Unity-ID-account-
https://support.unity3d.com/hc/en-us/articles/210620923-I-cannot-access-the-Unity-ID-accounts-pages
https://www.youtube.com/watch%3Fv%3DhN4MOvhZjNc
https://firebase.google.com/docs/auth/unity/google-signin
https://github.com/googlesamples/google-signin-unity
https://medium.com/teamarimac/how-to-develop-a-complete-leader-board-for-a-unity-game-using-firebase-facebook-sign-in-google-d865f577b303
https://codelabs.developers.google.com/codelabs/playservices_unity/index.html%3Findex%3D..%252F..index
https://chart.myunitypoint.org/
https://docs.microsoft.com/en-us/windows/uwp/xbox-live/get-started-with-creators/sign-in-manager