The server must support https, and the download source for each file must also use https.
Two PNG icons for the installed app: one 57*57 and one 114*114.
The files to access can be placed among the resources on a web server and accessed directly.
The files are autoninstall.html and dai.plist. The download page is https://idiot6.com/autoninstall.html (this domain is a test address and is not accessible).
Configure the doLocation URL in autoinstall.html, and the bundle-identifier, images, and title in dai.plist.
A serious pitfall: plist files are cached. If an upgrade or faulty configuration has already gone live, create a new plist file and update its path in autoinstall.html.