You mean the standard authentication doesn't work and produces this stacktrace?
Make sure you check all this: "Verify the server and instance names, check that no firewall is blocking UDP traffic to port 1434, and for SQL Server 2005 or later verify that the SQL Server Browser Service is running on the host."
Edit: Ok, but you entered the login and password to the Database entity you are loading in the DB replication? I think the App only supports normal MSSQL authentication.
For now i just went into the sql server management studio and created a sql server authentication login for mendix. The Standard windows authentication does not seem to work here.