That is a very very old product. It does not look like it is certified on that OS.
Forms 6i Documentation
220.127.116.11 Operating System
This version of Forms Developer requires Microsoft Windows. Specifically, one of the following versions:
Windows 95 (any version)
Windows 98 (any version)
Windows NT (Service Pack 5 or later)
For certification you should check with Middleware Certification (MOSC)
Forms and Reports 6i is not supported by Windows 7.
Refer: Forms / Reports Builder Certification on MS Windows 7 (Doc ID 1112213.1)
Since Forms 6i is already desupported, You will not get a direct download link on Oracle website. You may raise an SR for it.
Global Customer Support Engineer, Middleware Certification Support and Community Team