I have a WAB application that I built for field staff to access with a mobile web browser (chrome). When I share the URL for the WAB application it works fine if I use it on my desktop PC. However, when I click the link on my mobile phone, it opens in Chrome, prompts for my login, then after I enter my credentials, it brings me to my organization page/my content webpage, instead of loading the map. I don't have the "desktop site" option checked in chrome mobile browser.
I was finally able to get my map to load by clicking on the WAB application from the my contents page on my mobile browser. So I bookmarked it to my phones home screen. The next time I clicked on the bookmark, it prompted me to log in, then did the same thing and re-directed me to the my contents page instead of opening the map.
I had a someone with an iPhone X try the same link in safari browser, and it too redirected him to the my contents page instead of opening the web appbuilder map.