The AMYUNI PDF generator in FTM 16 will not work under Windows 7. This has nothing to do with Administrator rights per say but if you install the updater you then need to first run FTM as an Administrator. The link below has details.
You can install the updater and details are on the FTM KBhttp://ftm.custhelp.com/app/answers/detail/a_id/2777/kw/FTM%...
Note if you are running Windows 7 as 64 bit (unfortunately you don't advise this detail) the updater may not work. The KB article notes:
Note: These versions of Family Tree Maker are not designed to work on Vista or Windows 7 64-bit. Although you may find success using Family Tree Maker on a 64-bit operating system, we cannot offer any support for problems you may encounter in this environment. This article and patch will only work for Vista or Windows 7 32 bit.
An other alternative is to install a PDF generator, either Adobe Acrobat, or Nuance, or one of the many free ones and instead of exporting to PDF print and select the PDF driver as your printer.
Or update to FTM 2012 which will work correctly in Windows 7