Arcgis 10.5-10.6 have an issue with Pictometry where the image won't load. This issue is currently on Pictometry's end, but there's a solution. The latest version of pictometry(10.61-10.71) is actually compatible with Arcgis 10.5 and 10.6. You should just need to download the plugin add it by double clicking on the plugin and adding or by going to plugin manager via arcgis and then adding the plugin that way. May need to restart, but after that you should now be able to download the picture to arcgis.