Q. The installer refuses to run
A. Ensure Content Ratings for XF2.1+ is installed, as this add-on's installer requires it to be present.
Q. After installing, rating support is not enabled for XFMG
A. Please got to the Content => Content Ratings => Content support page and ensure the XFMG types are listed as "available" and "configured". If not click the "add default content types" button.
Then visit the Content => Content Ratings => Rating types page to allow the add-on a chance to recheck columns. For large amounts of content, it may present manual SQL to run.