SAML service provider side on C# without any addition plugin
Original code from https://github.com/onelogin/dotnet-saml
Modified for add addition "XML Request sign" and "Single logout request"
You can setting this Service provider project to connect with your IDP server by edit only appsettings.config file
If you still don't has any IDP for test connection I suggest tool from wso2carbon https://wso2.com/identity-and-access-management
This tool is very easy to use just download => extract => run => config and has example configuration in website