We have a 2016 on-premise that is not configured for IFD. The development team is attempting to build applications that can utilize the Web API however they are unsuccessful when trying to authenticate.
CRM 2016 On-Premise
Not configured for IFD
URL Redirects
ADFS claims authentication (forms is not enabled)
I have looked online for documentation about how to connect but I have not found definitive answers. In the given setup above, what is the method to authenticate?