I think that the source of the confusion is that a person can own the
full, standalone version of Acrobat (Distiller). FrameMaker also
provides a stripped-down version of Acrobat Distiller, which has fewer
features, but allows those who don't already own Acrobat to create PDFs
from within FrameMaker.
So, if you own the full version of Acrobat, install it. Then install
FrameMaker and reject the option to install Acrobat, Distiller, PDF
Creation add-on, or whatever it is called in your FM version. If you
install both the full version of Acrobat and the FM add-on version, you
will end up with a broken mess. If you don't own a full Acrobat version,
then you need to install the PDF add-on that comes with FrameMaker.
Also, if you install the full version of Acrobat, there should be never
be more than one version on your computer, and you should NOT also
install Adobe Reader or the FM PDF Creation add-on. Mixing
Acrobat/Reader versions, or mixing Acrobat with the PDF add-on is a
known recipe for trouble.