Regarding the Introducing Attachment Viewer! (https://www.arcgis.com/home/item.html?id=3ce375a56ed145bfa5e2214e2ad8983d ) I cant find the app in the list of templates? This is when I try to do this:
How to i get to add this to the template list? Is this a setting in our organisational account why it does not appear?
Looking at the screenshot in the comment that you left, it looks like you're not signed in when viewing the Attachment Viewer template. This would explain why you weren't able to see the 'Create a Web App' button on that page, but does not explain why you don't see the template in the template gallery.
It is possible that your Organization Administrator has changed the setting for configurable apps within your organization as there is a way to choose the configurable apps based on an existing group. Have the Admin navigate to the Organization tab > Settings > Map > Configurable Apps. To ensure that all of the current Esri Default configurable apps are available to users, this setting should say, "Esri Default". If it does, and you still cannot see the app template, the documentation reads that you may need to choose this again, and hit 'Save'.
Hope this helps!