itch.io

No need to apologize.  I don't think I've ever really used the resource manager so I'm not sure exactly how it handles the files, but here is the way I usually do it: first, copy over the image files from the sample maps to your project - you'll find them under img>characters, img>tilesets, and maybe also img>parallax.  Put these in the same folders in your project.

Open the sample maps in RPG Maker.  In the database, under the tileset tab, right click the name of the tileset and copy it.  Paste it into your project in an empty slot.  (You may need to increase maximum tilesets)  That will make sure you don't have to redo the tileset's passability and other settings.  After that, the tileset should be available to apply to one of your maps.  Hope this helps!