I usually use my broadcast account in Explicit Credentials section to connect to Client Test.
The way it works is adding User: Broadcast\[username] and cooperate password in order to connect. Domain is always empty for this connection.
However, apart from me, the rest of the team have SAML user in DM and in order to connect to Client Test, they need to use SAML credentials in Explicit Credentials section. We tried user:Sky\[firstname].[lastname] and cooperate password with empty domain section, but it failed authentication. We also tried different different combination of user and adding Sky as domain which it didn't work.
Note: because people are using their broadcast account to RDP to the server, Single sign-on doesn't work for them. Mainly because their user on DM is SAML user and their RDP user is broadcast user. so when using Sinle sign-on authentication on the Client Test, it's automatically tries to use their broadcast users for connection and that failed as broadcast user doesn't exist in DM.
I am able to log in to Client Test Tool through SAML by leaving all fields empty in explicit credentials. Doing this shows the small browser pop up like it does in cube when pressing "connect". "Force Authenticate Local User" needs to be unchecked however.
This behavior is only present starting from DataMiner version 10.3.5 however. On older versions it is more complicated to log in via external authentication in CTT, this would require capturing a SAML response and pasting it in the pop up that appears.