From https://server.arcgis.com/en/insights/latest/use/faq.htm#ESRI_SECTION3_6C33501DDE2F4EE78B658BAC180D10A7 "The page will be visible to all members of the public provided it is shared in a public format, such as a web page or a public Story Map."
At step 4, you need to use the embed code provided to add to a web page or story map. Data must be shared publicly to be seen