WD elements, "Not authorized"

I have a WD “Elements” external disk on which I put files from “computer A”. Next, I connect it to “computer B”. However, I cannot access it or even mount it (or change permissions) from “B”.
When I connect it to “computer A” I changed the permissions so that owner, group and others can read/write files on it.
What do I have to do to be able to access it from “computer B”?

Unfortunately, I cannot upload images in this post, so I will describe the menu of the “Elements” disk on “B”: Open / Open in New Tab / Open in New Window / Add Bookmark / (“Remove”) / (“Rename”) / Mount / Format…
When I click on Mount, I get the following message: "Unable to access “Elements”, Not authorized to perform operation.

Hi @MTXLubuntu,

Have you opened a Support Case? If not opened, for more information, please contact the WD Technical Support team for the best assistance and troubleshooting:
https://support-en.wd.com/app/ask