Testing the same link works https://res.cloudinary.com/acjoshi/image/fetch/w_200/q_auto:best/f_auto/https://arena.wien/EventDb-Images/GATECREEPER%20euro%20dark%20superstition%20tour%20flyer%20ALL%20DIGITAL.jpg?w=743&q=60

Note that while some characters have to be escaped for the sake of the browser, [/ and ,] must be double escaped for Cloudinary, as described here: http://support.cloudinary.com/hc/en-us/articles/202521512-How-to-add-a-slash-character-in-text-overlays-