We have been getting some cases in which Revit Content is not installing and is 'hanging'. There are some differences between the downloaded version or Revit from the Subscription Center and the DVD media. The downloaded version requires an internet connection to install Revit Content. The DVD version has the content on the media itself. In some instances, if it hangs, at Preparing Revit Content, if you disconnect your internet connection, the install will continue but it will skip the Revit Content.
I recently stumbed on this solution in which you add some settings to your browser to allow the installation to continue:
You can order the DVD media in the Download section in the Subscription Site. Thanks to Byron Morales and Danny Hubbard for assisting on this post.