How do I change the tag line in MDT from IT Organization?

You can set the text for the progress screen in your customs settings.

• In deployment bench right click MDT Deployment Share
• Select Properties
• Select Rules Tab
• In [Default] add _SMSTSORGNAME=”Enter your text here”

or edit the CustomSettings.ini file found in \DeploymentShare\Control

Lastly Update the Deployment Share in (Right click and select Update) in Workbench