This article's focus is on sharing why not to include images from online shared folders into SNB.
Copy and pasting images from online/shared locations is actually not copying an image but the link to the image, and as soon as a session is ended the link will not work, this is because you are expecting Signals Notebook to be able to login into places such as Google Photo library.
Also in scenarios where the user/organization is not in charge of the management of said location images can be updated or replaced and this means that the previously used link to the image will change and the relationship will be broken and you might see something like this ...
For how you should import/upload images to SNB please refer to the article How to add images into Signals Notebook