You will need to request these from your local B&R support. Older versions have been removed from the public download section due to regulatory compliance requirements related to EU dual-use export regulations.
More information available here:
How to Obtain Older Versions of Automation Studio [ AS2 | AS2.7 | AS3.0 | AS4.x ]
You can search for the closest B&R representative here:
Locations | B&R Industrial Automation