I have a local installation of SQL Server Management studio. I created a SQL Server Authentication login and tested it. However when I try to connect with Knime I get the following error
ERROR Microsoft SQL Server Connector 0:1 Execute failed: Login failed for user ‘testuser’. ClientConnectionId:282f7043-23d6-4ce8-9a17-763a2644ad20
That error message usually indicates that the client application, KNIME, is trying to connect using Windows/Trusted authentication, not SQL authentication like you have indicated your SQL Server is setup to use.