Only thumbnail size plus other obstacles

I thought I might have gotten that wrong in the widget settings and thus created a shortcode in order to get full-sized images, but it only grabs the tiny thumbnail version of images no matter what. Also, linking to the external images on Instagram only seems to work on a shortcode, so you actually cannot really use the widget. Since I see a lot of complaints and the latest update from a year ago, with no support in sight, I hereby post my first negative feedback on WP.org ever. Well deserved, sorry.