Resurfacing this thread with similar issue on AGOL.
If I create a Web Mapping application from the Map Viewer with Simple Viewer template, when shared the user is redirected to login page:
Using the same Web Map and procedure but with Minimalist template, the user has no problem accessing the web app:
The map itself can also be accessed:
Could there be a widget in the Simple Viewer causing the bug?
(I'm testing on Chrome in Incognito tabs)
I had the same issue in the Information Lookup template. The web app is embedded in our website as an iframe and there's also a hyperlink to it on the same page. The embedded iframe works with no problems, everything is shared publicly, no sign in required. When clicking the hyperlink, however, the app would open in another tab, and require a sign in. I opened the web map itself to test it and there were no issues opening it that way; something in the wep app template was forcing the sign in.
It finally worked after I went to configure the Information Lookup application we created and unchecked the 'Show the basemap selector' under Options. Now the hyperlink works on the website and does not require a sign in. When this option was checked, the basemap selector worked fine in the embedded iframe, but not with the hyperlink.
I hope this helps others.