You need to define at least one data model and one data container in the Studio for the Web Interface to work.
Use the URL:
http://localhost:8180/talendmdm/(replace localhost with the actual machine name if it is not running locally)
You may use the user/password: user / user.
Other valid users are in the login-config.xml file.
You may change the current data model and container by sliding open the collapsible panel on the right.
For more information about how to log in the Talend MDM Web User Interface, please download the Web User Interface User Guide in the User Manuals list of the product Download page on the Talend Website.