I can download an Adobe Stock image into my Adobe Asset Libraries, but not Adobe Assets directly. The reason I'm asking is because in the Mobile App Adobe Slate I can open up Adobe Assets to add images of which there are none because Adobe Slate does not provide access to Adobe Libraries within Adobe Assets. What can I do to provide a seamless access of images from Adobe Stock into Adobe Slate?
I don't know much about Adobe Slate. However, I tested the issue on Photoshop Mix and it works the same way. It gives option to upload images from "My Libraries" and "My Assets" both.
As far as Stock images are concerned, they are stored under the Libraries section of My Assets. So, you can use them from "My Library"directly.
If you need any specific information, in regards to Adobe Slate, would ask you to post your query here, https://standout.adobe.com/support/#slate