When trying to access the application I get prompted for credentials and then get a page with the below on it
Incorrect Kerberos constrained delegation configuration on the Active Directory.
If I then run Test application and the report gives the below results, which fails on step 5 Application Authentication
App report - Application Proxy
External Url Configuration
The external URL is reachable via the internet and correctly configured.
Azure AD Authentication
The current user is assigned to the application and can login to Azure AD or passthrough mode is used.
The connector is installed on your server and registered correctly with the Application Proxy service.
The connector can reach the backend application and recieve a response.
The user cannot authenticate to the single sign-on mode configured for the application.
Incorrect Kerberos constrained delegation configuration on the on-premises Active Directory.
To fix this problem you can:
Review your Single Sign-On settings in the portal and verify that the SPN is defined correctly in the portal as well as on the host machine.