Blahblah you were pretty close, just a couple of tweaks...
First the url you're trying isn't the location of the image file, it's just the location of the image in your cloud account - which opens the cloud editor/website. I don't see a way to view that image to get the url to it (they disable right-click, so they mean to prevent people from viewing the image file). You can download that image and upload it to an image hosting service like imgbb.com or imgur.com like this:
Download the image off your cloud account:
Then upload it to imgur, after upload I right-click on the image and open image in new tab:
Then the new tab has just the image file by itself, you can see in the url bar where the full url to the actual image file is:
Then you add the add-image button in the forums which pops up this code:
Which you'd update to look like this:
