Having issues setting up SAML / SHIB based in an organization

The error is “digest mismatch” so I cannot get past the test saml phase in the configuration ergo not able to save the SAML setup. I am being taken to the SSL login page and the IDP side shows a successful login. Please help, there is absolutely no clear documentation about this.

A Digest mismatch error can often occur when configuring GitHub Enterprise Cloud SSO if the IdP is using a different SAML Signing certificate than the one you have uploaded to your organization’s settings.