Fantasy Buildings by Mark Stern

NOTE  that this set includes PNG files. Many PNG files on one map have been known to slow down the load time and performance of many devices (especially older). For larger maps (above 15X15) or maps that will include many objects, it is recommended that you download the assets and put them together using an image-editing program such as Photoshop/GIMP, save the maps as JPEG files, and upload them to your Roll20 background. Cannot do that because of: i  Can only be used with Roll20; cannot be downloaded.

Despite that statement, the assets are in fact downloadable via the download PDF option: Apologies for any confusion, but typically a set has to be either an Addon or Downloadable, not both. Roll20 was gracious enough to allow me a one-time exception to this rule and used the Download PDF as a workaround to make it possible.  Hopefully, that clears things up for anyone that may acquire this set.