Having the same issue as @Built2Succeed
It was working fine until an update and now it doesn't connect to the dbase anymore and renders the page as seen in the screenshots from built2succeed. I setup a domain name before hand and set the url https as the instructions stated. Setup a dbase with MariaDB and tested working about a week ago. Still muddling through how to fix it, but I think I'm going to delete the app and redo everything. Not sure how to save what I have already put into Bookstack though.