>How can I distribute the app with a link for a hassle-free download, install and use for everybody?
You're out of luck as apple does not provide a casual distribution scheme that doesn't involve the store and/or testflight.
If you don't mind a 30-step process, however, you might get lucky via ad-hoc distribution.
Looks like iOS 12 will enhance TestFlight for casual distribution "And coming soon, you'll be able to invite testers to TestFlight with just a public link, access APIs to prepare your apps for the App Store, and more."
If you want to have a team building experience then a shared AR experience might be what you seek.
Recent versions of ARKit allow for shared AR experiences via ARWorldMaps.
For sample code and additional information on ARWorldMaps take a look at this year's ARKit WWDC session.