How can a user who is using their windows/network credentials login to team server using the same?

I am currently migrating ER Studio Team Server and Repository from 16 version to 18.5. In the 16 version, our client didn't have the LDAP set up and didn't use Team Server much but they want the users to connect to Team Server using their windows credentials like in Repository in 18.5 version. However, the user is currently not able to log in to the Team Server using the windows credentials.

As part of testing, I created myself as a user in repository through security center gave myself a password and a concurrent license through license server. I am able to login to Team Server and Repository using the same credentials. Can anyone help me understand the functionality and fix this for the user? They don't have any LDAP information with them and they are using something they call Enterprise Directory.

Product: ER Studio Team Server/Repository 18.5 Version and ER Studio Data Architect 18.5 version