The instructions you quoted are not clear. You would have to ask on a Kivy forum or mailing list to get clarification on what Resources folder they are talking about.
Generally an iOS or Mac app is an app bundle, which is a directory of files that looks like a single file in the Finder. If you select an app in your Mac's Application, right-click, and choose Show Package Contents, you can see how an app bundle is structured. An app bundle has a Resources folder, where image files would go.
What most iOS and Mac apps would do is copy image files to the Resources folder inside their app's app bundle, which Xcode creates when building the project. Adding the image files to the Xcode project should be enough to copy the files to your app bundle's Resources folder when building the project. But to make sure, check that the files are in the app target's Copy Bundle Resources build phase.
- Select the project from the left side of the project window to open the project editor.
- Select the app target from the list of targets on the left side of the project editor.
- Click the Build Phases button at the top of the project editosr.
- Click the disclosure triangle next to the Copy Bundle Resources build phase to see the files in the build phase.
- If the image files aren't in the Copy Bundle Resources build phase, click the Add (+) button at the bottom of the list of files to add the image files to the build phase.
Keep in mind that what I have described is how things work for native iOS and Mac projects. Kivy might do things differently. But the chances of finding someone on this forum who uses Kivy are slim. That is why you have to ask on a Kivy forum to get a definitive answer.
