Hi Michael Hart,
To show the widgets on selected pages you should follow the link as provided earlier https://www.styledthemes.com/flat-responsive-set…-selected-pages-only
and regarding not authorised to view the resource you should log in to view that source, and sometimes the cache problem doesn’t detects the user login so we recommend you to login from the same page which will solve the problem.
Do have a question if you have any?
Thanks.