That's correct, UE 4 supports only PHP. Part of the reason is the inclusion of Digital File Pro, the other reason is the general move away from classic ?asP which even Microsoft doesn't even support.
I still have a few sites in ASP, but I also have UE2 which I have to uninstall 4, then install 2 at times. I never did get ver 3, sort of skipped over that, but I would like to have it.
Most of what I use UE 4 for is simple contact forms, so I will be gradually switching over those contact forms in the ?asP sites to PHP forms. They can be mixed to that degree, if on separate pages and if the Windows server has PHP installed.