Go back to the root Databases folders, and then expand the Security folder, which should be just below it. From there, right click on the Logins subfolder and choose New Login. Again, give it the TestMakerFree name. From the radio button list below, select SQL Server Authentication, set a suitable password (for example, SamplePassword123), and then click on OK.
If you want a simpler password, such as OpenGameList, you might have to also disable the enforce password policy option. However, we advise against doing that; choosing a weak password is never a wise choice, especially if we do that in a production-ready environment. Instead, replace the sample password we used earlier with a custom one and store it carefully, we'll need it later on.