I just tried to connect my Google Apps Email and log into the Magix Cloud, so that I can save the files on Google Apps (i am assuming that is what it's for) and I get this error message:
First, there is no need to show an image by creating a link to an external host site. Simply click the "upload" button (blue circle with upwards pointing arrow) when creating or replying to any post and the image will appear within your post.
The error message you are showing is, I think, quite explicit. For whatever reason Google has not approved the link to Magix cloud. Your only solution is to ask Magix themselves about this, using this page.