The problem is link itself. Try to open any browser and check it leads to homepage, because there is no such PDF in your Media library. You need to upload it and then assign the link to the image.
Yes, all links both in short and full descriptions are indexed by Google.
As for Google, I meant this actual text box I am writing in now, not on the website. Will that link above be indexed in Google? If so, I will put all links in the ‘private content’ box below.
While your site is under development you would better discourage search engines from indexing your site sitehttp://prntscr.com/j7i4rr Navigate to Settings > Reading.
Put all the links into private content.
As I understood the problem with the link has been solved now, right?