There are two distinct workflows to consider. You sync Touch App projects to the Creative Cloud, and you also import CS files and images from your Creative Cloud account into Touch App Projects.
Touch App File Syncing—The latest iOS versions of Adobe Photoshop Touch, Proto, Ideas, and Collage support syncing. When syncing is turned on, the Touch App native app files are synced to the Creative Cloud on a per-app basis. For example, when you create a project in Photoshop Touch it syncs only a .psdx file to the Creative Cloud. In addition, these files are synced to your Creative Cloud Files folder on your computer. With the Touch App plug-ins installed, open these .psdx files in Photoshop.
Importing files—The new Touch Apps provide a few different ways for you to import the files you have in your Creative Cloud account. When you import, you can browse thumbnail renditions of the supported files in the Creative Cloud including PSDs, JPGs, PNGs, AIs, INDD, and others. When you import, the Creative Cloud creates a rendition and imports it into your project. These larger Adobe files are not synced to your iOS device.