You still should be able to use the plug-in. LR6 does not mark a big change in the application's architecture.
Be aware that there still are issues with the plug-in. Namely, some folks can't get the import to work at all, some hit issues with corrupt libraries, some are not getting GPS info, and not all Aperture previews are being copied, which is the only record you'll have of your Aperture-based edits.
Although you will get keywords for faces, with some consistency issues), you will not get coordinate references or Lightroom 6 faces functionality with your migrated photos.
Thanks for your advice. I'll try to fix it.